Conversion of boron nitride into n-type and p-type doped cubic boron nitride and structures

ABSTRACT

Using processes disclosed herein, materials and structures are created and used. For example, processes can include melting boron nitride or amorphous carbon into an undercooled state followed by quenching. Exemplary new materials disclosed herein can be ferromagnetic and/or harder than diamond. Materials disclosed herein may include dopants in concentrations exceeding thermodynamic solubility limits. A novel phase of solid carbon has structure different than diamond and graphite.

This application claims the benefit of U.S. Provisional Application No.62/202,202, entitled “SYNTHESIS AND PROCESSING OF Q-CARBON, GRAPHENE,NANODIAMOND, AND MICRODIAMOND BY NANOSECOND PULSED LASERS” and filed onAug. 7, 2015, U.S. Provisional Application No. 62/245,018, entitled“Synthesis and Processing of Q-Carbon, Single-Crystal Diamond Film, andSingle-Crystal Diamond Nanoneedles and Microneedles” and filed on Oct.22, 2015, U.S. Provisional Application No. 62/331,217, entitled “SYSTEMSAND METHODS FOR PROCESSING NANODIAMONDS AND OTHER NANOSTRUCTURES” andfiled on May 3, 2016, and U.S. Provisional Application No. 62/355,681,entitled “NANOSTRUCTURES AND METHODS FOR PROCESSING” and filed on Jun.28, 2016, which are incorporated herein by reference in their entirety.

This invention was made with government support under grant number1306400 awarded by the National Science Foundation. The government hascertain rights to this invention.

Embodiments relate generally to synthesis and processing of materialsand nanostructures, and more particularly, to synthesis and processingof novel phases of carbon (Q-Carbon) and boron nitride (Q-BN), anddirect conversion of carbon and BN into diamond and C-BN, respectively,including doped diamond and doped C-BN.

Using processes disclosed herein, materials and structures are createdand used. For example, processes can include melting boron nitride oramorphous carbon into an undercooled state followed by quenching.Exemplary new materials disclosed herein can be ferromagnetic and/orharder than diamond. Materials disclosed herein may include dopants inconcentrations exceeding thermodynamic solubility limits. A novel phaseof solid carbon has structure different than diamond and graphite.

Some embodiments include a process for creating nanostructures. Theprocess can include melting at least a portion of material into a superundercooled state. The process can also include quenching from the superundercooled state to form one or more nanostructures. The material canbe carbon (e.g., amorphous carbon) and the nanostructures formed caninclude diamond nanostructures. The material can be boron nitride (e.g.,hexagonal boron nitride) and the nanostructures formed can include cubicboron nitride nanostructures. The process can include, prior to themelting, depositing a film of the material on a substrate. The substratecan be adapted to provide a template for epitaxial growth such that thenanostructures are formed as epitaxial nanostructures (e.g., epitaxialdiamond nanostructures, epitaxial cubic boron nitride nanostructures,etc.). The material can be deposited on the substrate by pulsed laserdeposition. The melting can include melting at least a portion of thematerial using a nanosecond laser pulse. The melting and/or quenchingcan be performed in an environment at ambient temperature and pressure.

Some embodiments include a process for creating doped nanostructuresincorporating one or more dopants at concentrations exceedingthermodynamic solubility limits. The process can include depositing afilm and doping the film with one or more dopants. The process can alsoinclude melting at least a portion of the deposited, doped film into asuper undercooled state. The process can further include quenching fromthe super undercooled state to form one or more doped nanostructuresincorporating the one or more dopants at concentrations exceedingthermodynamic solubility limits. The dopants can be incorporated intothe doped nanostructures at concentrations exceeding thermodynamicsolubility limits via solute trapping. The material can be carbon (e.g.,amorphous carbon) and the nanostructures formed can be doped diamondnanostructures (e.g., n-type/p-type diamond and/or diamond havingnitrogen-vacancy (NV) centers). The material can be boron nitride (e.g.,hexagonal boron nitride) and the nanostructures formed can include dopedcubic boron nitride nanostructures. The film can be deposited on asubstrate that can be adapted to provide a template for epitaxial growthsuch that the doped nanostructures are formed as epitaxial dopednanostructures epitaxial n-type/p-type/NV diamond nanostructures,epitaxial n-type/p-type cubic boron nitride nanostructures, etc.). Thesubstrate can also be adapted placed deterministically on the substrate.The film can be deposited on the substrate by pulsed laser deposition.The melting can include melting at least a portion of the film using ananosecond laser pulse. The melting and/or quenching can be performed inan environment at ambient temperature and pressure.

Some embodiments include a material comprising a plurality of carbonatoms having an amorphous structure, the bond length of each of thecarbon atoms being less than 0.154 nm. The carbon-carbon bond lengthbetween the carbon atoms of the material can be between 0.142 and 0.154nm. The carbon-carbon bond length between the carbon atoms of thematerial can be between 0.142 and 0.146 nm. A first portion of theplurality of carbon atoms of the material can form a three dimensionalstructure. The first portion of the material can form a tetrahedralshape. The material can be stable up to 3330 K The material can have ahigher negative electron affinity than that of diamond. The negativeelectron affinity of the material can be at least seven percent greaterthan that of diamond. The material can be a semiconductor. The materialcan be metallic. The material can be harder than diamond.

Some embodiments include magnetic un-doped carbon. The magnetic un dopedcarbon can be ferromagnetic.

Some embodiments include a phase of carbon that has a structure that isdifferent than the structures of graphite and diamond.

Some embodiments include a phase of carbon having a higher negativeelectron affinity than diamond. The negative electron affinity can be atleast seven percent greater than that of diamond. The phase of carboncan be a semiconductor or metallic depending on a quenching rate from anundercooled state. The phase of carbon can be stable up to 3330 K.

Some embodiments include a material harder than diamond.

Some embodiments include a material comprising a plurality of carbonatoms having an amorphous structure with no long-range order, the bondlength of each of the carbon atoms being less than 0.154 nm. Thecarbon-carbon bond length between the carbon atoms of the material canbe between 0.142 and 0.154 nm. The carbon-carbon bond length between thecarbon atoms of the material can be between 0.142 and 0.146 nm. A firstportion of the plurality of carbon atoms can form a three dimensionalstructure. The first portion can form a tetrahedral shape.

Some embodiments include a process that includes depositing amorphouscarbon on a substrate. The process can include melting the amorphouscarbon into an undercooled state. The process can also include quenchingmelted amorphous carbon can be melted from the undercooled state tocreate Q-carbon, diamond, and/or graphene. In some embodiments, thequenching can create Q-carbon and diamond composite. In someembodiments, the quenching creates diamond. In some embodiments, thequenching creates graphene. In some embodiments, the quenching createsQ-carbon. In some embodiments, the process also includes melting theQ-carbon and quenching the melted Q-Carbon to create diamond. In someembodiments, the created diamond (e.g., diamond created directly byquenching from undercooled amorphous carbon or diamond formed frommelted Q-carbon) is a nanodot, nanodiamond, microdiamond, nanoneedle,microneedle, or large area single crystal film (ore portion thereof). Insome embodiments, the process includes using the substrate as a templatefor epitaxial growth. In some embodiments, the created diamond isepitaxial single crystal.

Some embodiments include a process that includes melting amorphouscarbon of an amorphous carbon film in an undercooled state by a laserpulse in an environment at ambient temperature and pressure. The processcan include quenching the amorphous carbon from the undercooled state toform Q-carbon, graphene, and/or diamond. The quenching can form adiamond/Q-carbon composite. The process can also include melting theQ-carbon and quenching the melted Q-Carbon to create diamond (e.g., ananodot, nanodiamond, microdiamond, nanoneedle, microneedle, or largearea single crystal film (or a portion thereof)). The process canfurther include depositing a film of amorphous carbon on a substrate.The process can also include using the substrate as a template forepitaxial growth. The created or formed diamond can be an epitaxialsingle crystal.

Some embodiments include a process for creating diamond. The process caninclude depositing a film of amorphous carbon on a substrate by pulsedlaser deposition. The process can also include melting a first portionof amorphous carbon of the amorphous carbon film in an undercooled stateby a first laser pulse. The process can also include quenching the firstportion of amorphous carbon from the undercooled state to form Q-carbon.The process can further include melting a first portion of the Q-carbonby a second laser pulse. The process can also include quenching themelted first portion of Q-Carbon to create a first diamond portion. Theprocess can also include melting a second portion of the Q-carbon by athird laser pulse. The process can also include quenching the meltedsecond portion of the Q-Carbon to create a second diamond portion. Thefirst and second portions of diamond can form at least a portion of ananodiamond, microdiamond, nanoneedle, microneedle, or large area singlecrystal film.

Some embodiments include a process for creating diamond and productsformed by the process. The process can include melting amorphous carboninto an undercooled state. The process can also include quenching theamorphous carbon from the undercooled state to create diamond. Thecreated diamond can be a nanodiamond, microdiamond, nanoneedle,microneedle, or large area single crystal film (or a portion thereof).The process can further include, before the melting, depositing a filmof the amorphous carbon on a substrate. The process can also includeepitaxially growing the created diamond using the substrate as atemplate for epitaxial growth. The substrate can be tungsten carbide,silicon, copper, sapphire, glass, or a polymer. The melting can includemelting amorphous carbon in an undercooled state by a laser pulse in anenvironment at ambient temperature and pressure.

Some embodiments include a process for creating diamond. The process caninclude melting a first portion of amorphous carbon into an undercooledstate by a laser pulse in an environment at ambient temperature andpressure. The process can also include quenching the first portion ofamorphous carbon from the undercooled state to create a first portion ofdiamond. The created first portion of diamond can be at least part of ananodiamond, microdiamond, nanoneedle, microneedle, gemstone, or largearea single crystal film. The process can further include, after thequenching the first portion, melting a second portion of amorphouscarbon into an undercooled state and quenching the second portion of theamorphous carbon to create a second diamond portion. The first andsecond portions of diamond can form a at least a portion of ananodiamond, microdiamond, nanoneedle, microneedle, gemstone, or largearea single crystal film. The process can further include, before themelting, depositing a film of the amorphous carbon on a substrate. Theprocess can also include epitaxially growing the first portion ofdiamond using the substrate as a template for epitaxial growth.

Some embodiments include a process for creating diamond. The process caninclude depositing a film of amorphous carbon on a substrate. Theprocess can also include melting a first portion of the amorphous carbonfilm in an undercooled state by a laser pulse in an environment atambient temperature and pressure. The process can also include quenchingthe first portion of the amorphous carbon film from the undercooledstate to create a first diamond portion using the substrate as atemplate for epitaxial growth. The process can further include, afterthe quenching the first portion, repositioning the laser pulse withrespect to the film or repositioning the film with respect to the laserpulse. The process can also include, after the repositioning, melting asecond portion of amorphous carbon in an undercooled state. The processcan also include, quenching the second portion of the amorphous carbonto create a second diamond portion using the substrate as a template forepitaxial growth. The first and second portions of diamond together canform at least part of a nanodiamond, microdiamond, nanoneedle,microneedle, gemstone, or large area single crystal film.

Some embodiments include a process for creating Q-BN. The process caninclude melting boron nitride into an undercooled state by a laser pulsein an environment at ambient temperature and pressure. The process canalso include quenching the undercooled boron nitride from theundercooled state to create Q-BN. The boron nitride can be hexagonalboron nitride. The melting can include nanosecond pulsed laser meltingat ambient temperatures and atmospheric pressure in air. The process canfurther include melting the Q-BN. The process can also include quenchingthe melted Q-BN to create cubic boron nitride. The process can alsoinclude depositing diamond on the cubic boron nitride by pulsed laserdeposition of carbon to create a cubic boron nitride and diamondheterostructure, the cubic boron nitride acting as a template forepitaxial diamond growth. The quenching the melted Q-BN can includequenching the melted Q-BN to create phase-pure cubic boron nitride. Theprocess can include, before the melting, depositing the boron nitride asa film on a substrate at room temperature. The substrate can be tungstencarbide, silicon, sapphire, glass, or a polymer. The created cubic boronnitride can be a nanodot, microcrystal, nanoneedle, microneedle or largearea single crystal film (or a portion thereof). The process can alsoinclude using the substrate as a template for epitaxial growth. Thelaser pulse can be a nanosecond laser pulse.

Some embodiments include a process for creating cubic boron nitride andproducts formed by the process. The process can include meltinghexagonal boron nitride into an undercooled state by a laser pulse in anenvironment at ambient temperature and pressure. The process can alsoinclude quenching the undercooled hexagonal boron nitride to createcubic boron nitride. The quenching can include quenching the undercooledhexagonal boron nitride to phase-pure cubic boron nitride. The processcan also include depositing a film of the hexagonal boron nitride on asubstrate and using the substrate as a template for epitaxial growth.The created cubic boron nitride can be a nanodot, microcrystal,nanoneedle, microneedle, or large area single crystal film (or a portionthereof). The substrate can be tungsten carbide, silicon, copper,sapphire, glass, or a polymer. The melting can include melting thehexagonal boron nitride in an undercooled state by a laser pulse in anenvironment at ambient temperature and pressure.

Some embodiments include a process for creating cubic boron nitride andproducts formed by the process. The process can include depositing afilm of hexagonal boron nitride on a substrate by laser pulsedeposition. The process can also include melting a first portion of thehexagonal boron nitride film into an undercooled state by a first laserpulse in an environment at ambient temperature and pressure. The processcan further include quenching the melted first portion of the hexagonalboron nitride film from the undercooled state to create a first cubicboron nitride portion. The process can also include moving the substratewith respect to an orientation of the laser pulse or moving theorientation of the laser pulse with respect to the film. The process canalso include melting a second portion of the hexagonal boron nitridefilm adjacent the first portion of the film into an undercooled state bya second laser pulse in an environment at ambient temperature andpressure; The process can further include quenching the melted secondportion of the hexagonal boron nitride film from the undercooled stateto create a second cubic boron nitride portion. The created first andsecond cubic boron nitride portions together forming at least part of ananodot, microcrystal, nanoneedle, microneedle, or large area singlecrystal film.

Some embodiments include a structure that includes a substrate and aplurality of NV-doped diamonds deterministically placed on thesubstrate. The plurality of NV doped diamonds can have a sameorientation. The plurality of NV-doped diamonds can be epitaxial withthe substrate.

Some embodiments include an NV-doped diamond having a concentration ofNV-dopants that exceeds thermodynamic solubility limits.

Some embodiments include a process for creating NV-doped diamond atambient temperature and pressure, the process including quenching carbonfrom an undercooled state to create the NV-doped diamond with NV-dopantconcentrations that exceed thermodynamic solubility limits.

Some embodiments include a process for creating NV-doped diamond havingsubstitutional nitrogen atoms and vacancies incorporated therein. Theprocess can include depositing an amorphous carbon film on a substrateby pulsed laser deposition. The process can also include adding N₂ ⁺ions to the deposited amorphous carbon film. The process can furtherinclude, after the adding, melting a portion of the film with the addedN₂ ⁺ ions into an undercooled state. The process can also includequenching the melted portion from the undercooled state to createNV-doped diamond having substitutional nitrogen atoms and vacanciesincorporated therein. The quenching can include rapid quenching from theundercooled state to create the NV-doped diamond with NV-dopantconcentrations that exceed thermodynamic solubility limits. The rapidquenching can include using solute trapping to create the NV-dopeddiamond with NV-dopant concentrations that exceed thermodynamicsolubility limits. The NV-doped diamond can have sharp transitionsbetween NV⁻ and NV⁰. The process can also include configuring thesubstrate to deterministically place the created NV-doped diamond on thesubstrate. The NV-doped diamond can have transitions between NV⁻ andNV⁰, and the transitions can be controlled electrically and/or opticallyby laser illumination. The duration of the quenching can be between200-250 nanoseconds. The process can also include epitaxially growingthe created NV-doped diamond by using the substrate as a template forepitaxial growth. The created NV-doped diamond can be a nanodot,microcrystal, nanoneedle, microneedle, or large area single crystal film(or a portion thereof).

Some embodiments include a large area single crystal film comprisingn-type doped diamond having a concentration of n-type dopants thatexceeds thermodynamic solubility limits.

Some embodiments include an N-type doped diamond having a concentrationof n-type dopants that exceeds thermodynamic solubility limits.

Some embodiments include a process for creating n-type and/or p-typediamond and products formed by the process. The process can includedoping amorphous carbon with n-type and/or p-type dopants. The processcan also include melting the doped amorphous carbon into an undercooledstate. The process can further include quenching the melted amorphouscarbon from the undercooled state to create n-type and/or p-type dopeddiamond. The n-type and/or p-type dopants can be incorporated intoelectrically active substitutional sites of the created diamond withconcentrations exceeding solubility limits via solute trapping. Theprocess can include, before the melting, depositing the amorphous carbonas a film on a substrate. The process can further include using thesubstrate as a template for epitaxial growth of the created n-typeand/or p-type doped diamond. The created n-type and/or p-type dopeddiamond can be a nanodot, nanodiamond, microdiamond, nanoneedle,microneedle, or large area single crystal film (or a portion thereof).The melting can include melting the doped amorphous carbon into anundercooled state by a laser pulse in an environment at ambienttemperature and pressure. The quenching can include quenching the meltedamorphous carbon from the undercooled state to create n-type and/orp-type doped diamond in an environment at ambient temperature andpressure.

Some embodiments include a process for creating n-type and/or p-typediamond and products formed by the process. The process can includedepositing a film of amorphous carbon on a substrate. The process canalso include doping the amorphous carbon film with n-type and/or p-typedopants. The process can further include melting the doped amorphouscarbon in an undercooled state by a laser pulse. The process can alsoinclude quenching the melted amorphous carbon from the undercooled stateto form n-type and/or p-type doped diamond using the substrate as atemplate for epitaxial growth. The n-type and/or p-type dopants can beincorporated into electrically active substitutional sites of thecreated diamond with concentrations exceeding solubility limits viasolute trapping.

Some embodiments include a process for creating n-type and p-typediamond and products formed by the process. The process can includedepositing a film of amorphous carbon on a substrate. The process canalso include doping at least a first portion of the amorphous carbonfilm with first dopants, the first dopants being n-type or p-typedopants. The process can further include melting at least a firstportion of the doped first portion of the amorphous carbon film into anundercooled state by a laser pulse. The process can also includequenching the melted first portion from the undercooled state to form afirst doped diamond portion using the substrate as a template forepitaxial growth. The process can also include doping at least a secondportion of amorphous carbon with second dopants. The second dopants canbe n-type or p-type dopants. The second dopants can be different thanthe first dopants (e.g., the first dopants can be one type of the twotypes (n-type and p-type), and the second dopants can be the othertype). The process can also include melting at least a second portion ofthe doped second portion of amorphous carbon into an undercooled stateby a laser pulse. The process can further include quenching the meltedsecond portion from the undercooled state to form a second doped diamondportion. The first and second dopants can be incorporated into the firstand second doped diamond portions respectively at concentrationsexceeding solubility limits via solute trapping. The first and seconddoped diamond portions can together form at least a portion of a p-njunction. The film can comprise the second portion of amorphous carbon,or the process can also include depositing, after quenching the meltedfirst portion, a second film of the second portion of amorphous carbon.

Some embodiments include a process for creating n-type and/or p-typecubic boron nitride and products formed by the process. The process caninclude doping boron nitride with n-type and/or p-type dopants. Theprocess can also include melting the doped boron nitride in anundercooled state. The process can further include quenching the meltedboron nitride from the undercooled state to form n-type and/or p-typedoped cubic boron nitride. The boron nitride can be hexagonal boronnitride. The n-type and/or p-type dopants can be incorporated intoelectrically active substitutional sites of the created cubic boronnitride with concentrations exceeding solubility limits via solutetrapping. The process can also include, before the melting, depositingthe boron nitride as a film on a substrate. The process can furtherinclude using the substrate as a template for epitaxial growth of thecreated n-type and/or p-type doped cubic boron nitride. The createdn-type and/or p-type doped cubic boron nitride is a nanodot,microcrystal, nanoneedle, microneedle, or large area single crystal film(or a portion thereof). The melting can include melting the doped boronnitride in an undercooled state by a laser pulse in an environment atambient temperature and pressure. The quenching can include quenchingthe melted boron nitride from the undercooled state to create n-typeand/or p-type doped cubic boron nitride in an environment at ambienttemperature and pressure.

Some embodiments include a process for creating n-type and/or p-typecubic boron nitride and products formed by the process. The process caninclude depositing a film of hexagonal boron nitride on a substrate. Theprocess can also include doping the hexagonal boron nitride film withn-type and/or p-type dopants. The process can further include meltingthe doped boron nitride in an undercooled state by a laser pulse. Theprocess can also include quenching the melted boron nitride from theundercooled state to form n-type and/or p-type doped cubic boron nitrideusing the substrate as a template for epitaxial growth. The n-typeand/or p-type dopants can be incorporated into electrically activesubstitutional sites of the created cubic boron nitride withconcentrations exceeding solubility limits via solute trapping.

Some embodiments include a process for creating n-type and p-type cubicboron nitride and products formed by the process. The process caninclude depositing a film of boron nitride (e.g., hexagonal boronnitride) on a substrate. The process can also include doping at least afirst portion of the boron nitride film with first dopants, the firstdopants being n-type or p-type dopants. The process can further includemelting at least a first portion of the doped first portion of the boronnitride film into an undercooled state by a laser pulse. The process canalso include quenching the melted first portion from the undercooledstate to form a first doped cubic boron nitride portion using thesubstrate as a template for epitaxial growth. The process can alsoinclude doping at least a second portion of boron nitride with seconddopants. The second dopants can be n-type or p-type dopants. The seconddopants can be different than the first dopants (e.g., the first dopantscan be one type of the two types (n-type and p-type), and the seconddopants can be the other type). The process can also include melting atleast a second portion of the doped second portion of boron nitride intoan undercooled state by a laser pulse. The process can further includequenching the melted second portion from the undercooled state to form asecond doped cubic boron nitride portion. The first and second dopantscan be incorporated into the first and second doped cubic boron nitrideportions respectively at concentrations exceeding solubility limits viasolute trapping. The first and second doped cubic boron nitride portionscan together form at least a portion of a p-n junction. The film cancomprise the second portion of boron nitride, or the process can alsoinclude depositing, after quenching the melted first portion, a secondfilm of the second portion of boron nitride.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

FIG. 1A is a graph depicting an example of a carbon phase diagram.

FIG. 1B is a graph depicting Gibbs free energy as a Function ofTemperature for Graphite (G_(g)), Liquid Carbon (G_(lia)) and Diamond(G_(d)).

FIG. 2 is a top view of a scanning electron microscope (“SEM”)micrograph showing a cellular structure of a Q-carbon filament.

FIG. 3 is an image showing formation of a nanodiamond.

FIG. 4 is a top view of an SEM micrograph showing growth ofmicrodiamonds from a Q-carbon filament that contained nanodiamondnuclei.

FIG. 5 is a top view of an SEM micrograph showing an area near themiddle of an irradiated amorphous carbon that includes a high density ofnanodiamonds and microdiamonds.

FIG. 6 is a top view of an SEM micrograph showing formation ofnanodiamonds from a Q-carbon.

FIG. 7 is a top view of an SEM micrograph showing an area near themiddle of an irradiated amorphous carbon that includes mostlymicrodiamonds.

FIG. 8 is a top view of an SEM micrograph showing a Q-carbon filamentgrowing microdiamond through the growth of nanodiamonds.

FIG. 9 is a top view of an SEM micrograph showing formation ofnanodiamonds by homogeneous nucleation and on top of existingmicrodiamonds formed by heterogeneous nucleation (shown by arrows).

FIG. 10 is a top view of an SEM micrograph showing formation ofnanodiamonds by homogeneous nucleation between Q-carbon filaments.

FIG. 11 is a top view of SEM micrograph showing diamond nanodots andnanorods nucleating from Q-carbon.

FIG. 12 is a top view of an SEM micrograph showing microdiamonds formingwhen most of a Q-carbon filament is converted into diamond by secondlaser pulse.

FIG. 13 is a top view of an SEM micrograph showing a full conversion ofamorphous Q-carbon into a string of microdiamonds.

FIG. 14 is a top view of an SEM micrograph showing a triple point of aQ-carbon filament and the nucleation of diamond.

FIG. 15 is a top view of an SEM micrograph showing heterogeneousnucleation of nanodiamonds after a laser pulse is applied to theQ-carbon.

FIG. 16 is a top view of an SEM micrograph showing formation ofmicrodiamonds and some nanodiamonds after a second laser pulse isapplied to the Q-carbon filament.

FIG. 17 is a top view of an SEM micrograph showing microdiamondscovering an entire region of super undercooled carbon.

FIG. 18 is a top view of an SEM micrograph showing formation of alarge-area single-crystal diamond thin film on a sapphire substrate.

FIG. 19 is an image of an SEM micrograph showing diamond growing on acopper substrate, where diamond is epitaxially aligned with copper andgrows as single crystal.

FIG. 20 is an image of an SEM micrograph showing the formation of adiamond faceted pillar 2002 from super undercooled carbon.

FIG. 21 is a graph 2100 depicting an example of Raman spectra resultsfrom Q-carbon on a sapphire substrate after a laser pulse, according toone example.

FIG. 22 is a graph 2200 depicting an example of Raman spectra resultsfrom microdiamond on sapphire substrate after a laser pulse, accordingto one example.

FIG. 23 is an image of an SEM micrograph image showing a cross-sectiontransmission electron microscopy (“TEM”) sample of Q-carbon containingnanodiamonds and microdiamonds on a sapphire substrate, according to oneexample.

FIG. 24 is a high-resolution TEM (“HRTEM”) image showing a diamondmicrocrystallite and the corresponding <110> electron diffractionpattern, according to one example.

FIG. 25 is a HTREM image from Q-carbon that has a substantiallyamorphous structure with some nanodiamonds embedded into the Q-carbon.

FIG. 26 is a graph of an electron energy loss spectroscopy (“EELS”)spectrum from diamond, according to one example.

FIG. 27 is a graph of an EELS spectrum from Q-carbon, according to oneexample.

FIG. 28 is a schematic diagram showing formation of diamond nanoneedlesor microneedles from super undercooled carbon.

FIG. 29 is an SEM micrograph showing formation of diamond nanoneedlesand diamond microneedles from super undercooled carbon.

FIG. 30 is an SEM image with EBSD Kikuchi pattern from microdiamondgrowing out of super undercooled carbon, according to one example.

FIG. 31 is an SEM image with EBSD Kikuchi pattern from a nanoneedlegrowing out of super undercooled carbon near a sapphire interface,according to another example.

FIG. 32 is an image of an SEM micrograph showing diamond microneedlesforming from super undercooled carbon with an EBSD pattern.

FIG. 33 is a graph depicting an example of Raman spectrum results fromdiamond microneedles.

FIG. 34 is an SEM micrograph showing diamond nanoneedles andmicroneedles growing from super undercooled carbon on a sapphiresubstrate, according to one example.

FIG. 35 is an image of an SEM micrograph after residual amorphous carbonis etched away, which shows that nanoscale perturbation sets in quenchedsuper undercooled carbon liquid.

FIG. 36 is an image of a SEM micrograph after residual amorphous carbonis etched away, which shows formation of diamond nanoneedles andmicroneedles from super undercooled carbon.

FIG. 37 is an image of a SEM micrograph showing formation of nanoneedlesand microneedles from super undercooled carbon after residual amorphouscarbon is etched away, according to another example.

FIG. 38 is a graph depicting an example of Raman spectra results fromnanodiamond, microdiamond and large-area thin films without residualamorphous peaks.

FIG. 39 is an image of a SEM micrograph showing microdiamonds andnanodiamonds on a high density polyethylene (HDPE) substrate.

FIG. 40 is a graph depicting an example of Raman spectra results beforeand after laser annealing an amorphous diamond-like carbon film from theHDPE substrate depicted in FIG. 39.

FIG. 41 is a flow chart depicting an example of a process for convertingsuper undercooled carbon into a phase of carbon (e.g., Q-carbon) fromwhich diamond structures can grow or nucleate.

FIG. 42 is a graph depicting an example of bulk ferromagnetism incarbon, according to one example.

FIG. 43 is a graph showing Kelvin Probe Force Microscopy (“KPFM”) onQ-carbon compared to a matrix of diamond and diamond-like carbon.

FIG. 44 is a graph showing resistivity of amorphous carbon and Q-carbonas function of temperature.

FIG. 45 is a graph depicting an example of Raman spectra results fromQ-carbon after multiple laser pulses, showing high-temperature stabilityof Q-carbon

FIG. 46 is a flow chart depicting an example of a process forintegrating a diamond structure with a substrate.

FIG. 47 is a graph depicting an example of a boron nitride phase diagramcontaining cubic boron nitride (c-BN), hexagonal boron nitride (h-BN)and liquid boron nitride.

FIG. 48 is a graph depicting an example of Raman spectra results beforeand after laser annealing h-BN to convert h-BN into phase-pure c-BN.

FIG. 49A shows formation of super undercooled EN from which nano- andmicro-cBN crystallites are formed.

FIG. 49B shows Q-BN converted into nanocrystalline films.

FIG. 49C shows Q-BN converted into large-area <111> platelets.

FIG. 49D shows Q-BN converted into single-crystal thin films.

FIG. 50A shows formation of nanoneedles and microneedles of cBN.

FIG. 50B shows a mechanism of formation of nanoneedles and microneedlesof cBN.

FIG. 50C shows initial stages of formation of nanoneedles andmicroneedles as a result of interfacial instability.

FIG. 50D shows a large-area single crystal thin film formed in themiddle for a laser beam.

FIG. 51 illustrates the atomic structure of substitutional nitrogen andvacancy (NV) defect in <110> chain of diamond.

FIG. 52 illustrates an NV defect in a diamond tetrahedron contained in(a/2, a/2, a/2) diamond unit cell.

FIG. 53 is a high-resolution SEM micrograph of nanodiamonds with insetat a higher magnification, according to one example.

FIG. 54 is a high-resolution SEM micrograph of a mechanism ofnanodiamond formation from Q-Carbon, according to one example.

FIG. 55 is a high-resolution SEM micrograph of the formation ofnanodiamonds during initial stages and EBSD pattern, showingcharacteristic diamond Kikuchi pattern, according to one example.

FIG. 56 is a high-resolution SEM micrograph of a mixture of nanodiamondsand microdiamonds, according to one example.

FIG. 57 is a high-resolution SEM micrograph of microdiamonds coveringthe entire area with inset showing twins whose density is controlled byquenching rates, according to one example.

FIG. 58 shows nanoneedles and microneedles from pure undoped sample withinset characteristic diamond EBSD pattern and orientation from the spotindicated, according to one example.

FIG. 59 is a high-resolution SEM micrograph of nanodiamonds, flatnanodiamond nanoplates, and perpendicular nanoplates of diamond withinset diamond EBSD Kikuchi pattern and orientation, according to oneexample.

FIG. 60 is a high-resolution SEM micrograph of a mixture of nanodiamondsand nanoplates of diamond, according to one example.

FIG. 61 is a high-resolution SEM micrograph of microdiamonds fromN-doped samples containing twins, according to one example.

FIG. 62 shows nanoneedles and microneedles from N-doped sample withinset characteristic diamond pattern and orientation, according to oneexample.

FIG. 63 shows Raman spectra for different N-doping by varying nitrogenpressure after laser treatment, including undoped control sample,according to one example.

FIG. 64 shows Raman spectra for different N-doping by changing the N₂ ⁺ion flux after laser treatment, including the control (before laserannealing) sample, according to one example.

FIG. 65 shows Raman spectra for change in Raman shift, down shift due tosize (nanorange) and upshift as a result of quenched-in stress,according to one example.

FIG. 66 shows a PL spectrum containing ZPL from NV⁻ (637 nm) and NV⁰(575 nm) defects, with an inset (100× magnification) showing transitionswhen the sample is irradiated with 532 nm PL source.

FIG. 67 shows Carrier concentration plotted as 1/T.

FIG. 68 shows Hall mobility as a function of T.

FIG. 69 shows a quantum spin phasemeter for magnetic field detectionbased on Q-Carbon, according to one example.

FIG. 70 shows a Q-Carbon as metallic ferromagnetic layer in spin-torqueoscillator, according to one example.

FIG. 71 shows a Q-Carbon optical lock, according to one example.

FIG. 72 shows a Q-Carbon memory unit based on bistability underparamagnetic (“PM”)-ferromagnetic (“FM”) phase transition, according toone example.

FIG. 73 shows graphene, reduced graphene oxide and diamond integratedwith silicon and sapphire, according to one example.

FIG. 74 is a flow chart depicting an example of a process for quenchingfrom a super undercooled state to form one or more structures ofmaterial.

FIG. 75 is a flow chart depicting an example of a process for quenchingfrom a super undercooled state to form one or more structuresincorporating one or more dopants at concentrations exceedingthermodynamic solubility limits.

DETAILED DESCRIPTION

Certain aspects and features of the present disclosure are directed toconverting carbon into graphene, diamond, and/or a phase of carbon fromwhich diamond structures can grow or nucleate. In some examples, thephase of carbon can be referred to as quenched-in carbon (“Q-Carbon”).Q-carbon can include nanodiamond nuclei, which can provide a seed forgrowth of nanodiamond, microdiamond, single crystal diamond nanoneedlesor microneedles, and single-crystal diamond films.

Carbon can be converted to Q-carbon by pulsed laser annealing andutilizing energy densities in the melting regime. In some examples,carbon can be directly converted into Q-carbon by irradiating a carbonfilm with a nanosecond laser. The carbon film can be on a substrate(e.g., a sapphire, glass, plastic, polymer, tungsten carbide, silicon,copper, stainless steel, or titanium nitride substrate). The laser canmelt the carbon film and create a highly undercooled phase. The highlyundercooled phase can cause a highly undercooled carbon layer to formnear the carbon film and substrate interface. The carbon film can becooled and retained at room temperature. Cooling the carbon film fromthe highly undercooled phase to room temperature can form a phase ofcarbon (e.g., Q-carbon). Q-carbon can be a state of solid carbon with ahigher mass density than amorphous or diamond-like carbon. The Q-carboncan have a structure that has a mixture of four-fold sp³ bonded carbonand some three-fold sp² bonded carbon. In some examples, the relativefraction for sp³ bonded carbon can vary from seventy percent toeighty-five percent. The Q-carbon can have enhanced mechanical,chemical, and physical properties, including, for example, enhancedhardness, enhanced electrical conductivity, enhanced room-temperatureferromagnetism (“RTFM”), enhanced field emission, and enhanced electronemission (e.g., negative electron affinity). In some examples, theQ-carbon can be harder than diamond. For example, from covalent bondlength determinations, the Q-carbon may be harder than diamond. As anexample, the Q-carbon may have a shorter average carbon-carbon lengththan diamond (e.g., less than 0.154 nm). For example, the averagecarbon-carbon bond length can be between 0.142 nm and 0.146 nm. Asanother example, the average carbon-carbon length can be between 0.142nm and 0.154 nm. In some examples, the Q-carbon may be a semiconductor.In other examples, the Q-carbon can be metallic. In still anotherexample, the Q-carbon may exhibit robust ferromagnetism.

In some examples, nanodiamond nuclei can be embedded in the Q-carbon.The nanodiamond nuclei and lattice matching substrates can provide aseed for growth of a diamond microstructure, diamond nanostructure, orsingle-crystal diamond sheet. For example, the nanodiamond nuclei canprovide a seed for growth of a nanodiamond, microdiamond, single-crystaldiamond nanoneedle or microneedle, or large-area single-crystal diamondsheet. In some examples, a subsequent laser pulse can be applied to theQ-carbon. The subsequent laser pulse can cause nanodiamond on theQ-carbon to grow into microdiamond and nucleate other diamond structures(e.g., diamond nanoneedles, diamond microneedles and large-areasingle-crystal diamond sheets) on the microdiamond.

Diamond microstructures, diamond nanostructures, and single-crystaldiamond sheets can be formed from super undercooled carbon depending onvarious factors, including, for example, the nucleation time and thegrowth time allowed for diamond formation, laser parameters, or theproperties and characteristics of the substrate. Table 1, shown below,provides example parameters for forming diamond structures using ArFExcimer laser (193 nm wavelength and 20 ns pulse duration). The thermalconductivity of the substrate should be low enough to confine the laserenergy into the carbon film.

TABLE 1 Parameters for diamond growth from super undercooled carbonusing ArF (193 nm wavelength and 20 ns pulse duration) Excimer LaserStructure Nucleation/Growth time Laser Parameters Nanodiamond   1-5 ns0.5 Jcm⁻²-0.8 Jcm⁻² Microdiamond  50-100 ns 0.6 Jcm⁻²-0.8 Jcm⁻²Nanoneedle 100-150 ns 0.5 Jcm⁻²-0.8 Jcm⁻² Microneedle 200-250 ns 0.5Jcm⁻²-0.8 Jcm⁻² Single-crystal film 100-250 ns 0.6 Jcm⁻²-0.8 Jcm⁻²

The diamond microstructures, nanostructures, and single-crystal sheetcan each be integrated on a substrate (e.g., a silicon or plasticsubstrate). Diamond structures formed from Q-carbon can have variousenhanced characteristics including, for example, enhanced electronemission properties.

In some examples, carbon can be converted into Q-carbon at ambienttemperatures (e.g., room temperature) and atmospheric pressure in air(e.g., pressure of a surrounding medium, including, for example, air).The conversion of carbon to Q-carbon may occur in the absence of anycatalyst or in the absence of hydrogen. For example, carbon can beconverted into Q-carbon by irradiating an amorphous (e.g., diamond-like)carbon film with a nanosecond laser. The laser can provide a nanosecondlaser pulse that can melt the amorphous carbon film. Using thenanosecond laser pulses to melt the amorphous carbon film can create ahighly undercooled state, which can cause a highly undercooled carbonlayer to form near an interface between the carbon film and thesubstrate. Quenching the carbon while in the highly undercooled statemay cause the highly undercooled carbon layer to break into a cellular(e.g., filamentary) structure, which can create Q-carbon from whichvarious forms of diamond can be formed. The diamond can be in the formof a nanodiamond (e.g., a diamond that has a size range of less than 100nanometers (nm)). In another example, carbon can be converted intodiamond in the form of a microdiamond (e.g., a diamond that has a sizerange of greater than 100 nm). In still another example, carbon can beconverted into diamond in the form of a nanoneedle or microneedle. Insome examples, a diamond microneedle can have a length of up to 2000 nm.In another example, a diamond microneedle or diamond nanoneedle may be adiamond with a diameter between 80 nm to 500 nm and a length between2000 nm to 3000 nm. In other examples, diamond microstructures can beformed from the Q-carbon including, for example, diamond nanodots,nanorods, or large-area single-crystal diamond films.

In some examples, creating a highly undercooled state of amorphouscarbon can modify the equilibrium phase diagram of carbon. For example,creating the highly undercooled state can shift the graphite, diamond,and liquid carbon triple point from a high-pressure and temperature tolow pressures and temperatures. Quenching or cooling the amorphouscarbon from the highly undercooled state can cause a nanodiamond tonucleate. In some examples, a microdiamond may grow out of the highlyundercooled state of the amorphous carbon. For example, a nanodiamondmay act as a seed crystal for growing the microdiamond. In certainexamples, diamonds formed from the amorphous carbon may have variousenhanced characteristics and properties (e.g., ferromagnetism atroom-temperature and higher, enhanced hardness, enhanced electronemission and catalytic properties).

In some examples, an amorphous metastable phase of carbon can beconverted into Q-carbon at ambient temperatures and atmospheric pressurein air. The amorphous carbon can include bonding characteristics thatmay be a mixture of graphite (e.g., sp² bonded) and diamond (e.g., sp³bonded). In some examples, the amorphous carbon can be on a substrate,including, for example, a sapphire, a plastic or a glass substrate. Theamorphous carbon can be melted at a low temperature (e.g., at 4000K ormore than 1000K below the melting point of crystalline carbon orgraphite) to create a highly undercooled state of carbon liquid. In someexamples, the highly undercooled state can be created by irradiating theamorphous carbon using a nanosecond laser. The laser can be a nanosecondExcimer pulsed laser or an equivalent energy source (e.g., ArF Excimerlaser (wavelength 193 nm or photon energy of 6 eV and pulse duration 20ns)). Nanosecond laser pulses from the laser can melt the amorphouscarbon film and create the highly undercooled state. The highlyundercooled state can cause a highly undercooled carbon layer to formnear an interface between the carbon film and the substrate. In someexamples entire layer of carbon can be converted into the Q-carbonphase. In some examples, diamond nanocrystallites can be nucleated fromfour-fold coordinated (sp³ bonded) carbon present in the highlyundercooled state of the amorphous carbon. Undercooling the amorphouscarbon can shift the amorphous carbon, diamond, and liquid carbon triplepoint to 4000K or lower at ambient pressures (e.g., pressure of asurrounding medium). At temperatures below 4000K, Gibbs free energy ofamorphous carbon can equal the free energy of highly undercooled liquidand metastable diamond phase that is quenched and retained at roomtemperature. In some examples, the amorphous carbon can be metallic inthe highly undercooled state, which can cause the carbon atoms to beclosely packed with a significant shrinkage. In some examples, packingthe carbon atoms can cause the amorphous carbon to have a mass densityand hardness that is greater than that of diamond. The amorphous carboncan be quenched to room temperature after a period of time in theundercooled phase. Quenching the amorphous carbon from the undercooledphase to room temperature can form Q-carbon. A subsequent laser pulsecan be applied to the Q-carbon. The subsequent laser pulse can melt theQ-carbon and create a highly undercooled state. The Q-carbon can bequenched from the highly undercooled state to room temperature.Quenching the Q-carbon can form diamond microstructures, diamondnanostructures, and single-crystal diamond sheets. Diamondmicrostructures, diamond nanostructures, and single-crystal diamondsheets may be formed depending on a number of factors, including, forexample, parameters of the nanosecond pulsed laser, orientation of thesubstrate, the amount of time in the undercooled phase, nucleation timeand growth time allowed for diamond formation, etc.

In some examples, shrinkage and internal melting of the amorphous carbonwhile in the undercooled state can cause bubbles to form. The bubblesmay burst and allow a single-crystal diamond microneedle or nanoneedleto grow out of the bubbles, depending on a size of the bubble. Inanother example, a microneedle can be formed from the Q-carbon throughexplosive recrystallization, where nanodiamonds nucleate from theQ-carbon and grow rapidly by liquid mediated explosiverecrystallization. In some examples, a diamond microneedle can have alength of up to 2000 nm. In another example, a diamond microneedle ornanoneedle may be a diamond with a diameter between 80 nm to 500 nm anda length between 2000 nm to 3000 nm. In some examples, the diamondmicroneedle or nanoneedle may have a growth velocity between 5 ms⁻¹ and10 ms⁻¹. In another example, the diamond microneedle or nanoneedle mayhave a melt lifetime between about 250 ns to 500 ns.

In certain examples, nanodiamond crystals can nucleate from theundercooled state and can provide a seed for growth of nanodiamond,microdiamond, diamond nanoneedles, diamond microneedles, orsingle-crystal diamond films. In some examples, the undercooling statemay be retained for a sufficient period of time to allow nanodiamond,microdiamond, diamond nanoneedles, diamond microneedles, orsingle-crystal diamond films to nucleate and grow.

The laser heating of the amorphous carbon can be confined spatially andtemporally. Confining the laser heating of the amorphous carbon canallow diamond structures (e.g., microdiamonds, nanodiamonds, diamondmicroneedles, diamond nanoneedles, diamond films, etc.) formed from theamorphous carbon to be deposited on heat-sensitive substrates (e.g., lowthermal conductivity substrates, including, for example, sapphire,silicon, plastic, or glass). In another example, converting carbon intoQ-carbon, nanodiamond, microdiamond, diamond nanoneedles, diamondmicroneedles, or single-crystal diamond films can allow the integrationof diamond thin film based devices with silicon based microelectronicand nanoelectronic devices.

Directly converting carbon into diamond at ambient pressures andtemperatures in air can increase production volume of diamond and canreduce costs associated with producing diamonds. Directly convertingcarbon into diamond at ambient pressures and temperatures in air mayalso enhance the synthesis and processing of nanodiamonds andmicrodiamonds for various applications, including, for example, abrasivepowders, protective coatings, catalytic properties, display devices,biomedical and microelectronic and nanoelectronic applications,photonics, etc. Directly converting carbon into diamond nanoneedles andmicroneedles may enhance the production of field emission based devicesand may be beneficial for biomedical applications (e.g., minimallyinvasive transdermal medical devices for various applications,including, for example, drug delivery, fluid sampling, micro-dialysis,electrochemical sensing, etc.). In other examples, directly convertingcarbon into large area single-crystal diamond films can allow n-typedoping (e.g., adding an impurity that contributes free electrons andincreases conductivity) and p-type doping (e.g., adding an impurity thatcan create a deficiency of valence electrons) of the diamond films,which may enhance the processing of high-power devices and high-powertransistors.

These illustrative examples are given to introduce the reader to thegeneral subject matter discussed here and are not intended to limit thescope of the disclosed concepts. The following sections describe variousadditional features and examples with reference to the drawings in whichlike numerals indicate like elements, and directional descriptions areused to describe the illustrative examples but, like the illustrativeexamples, should not be used to limit the present disclosure.

FIG. 1A is a graph depicting an example of a carbon phase diagram 100.The carbon phase diagram 100 includes an inset 102. Inset 102 depicts anexample of a carbon phase diagram at low pressures. In the carbon phasediagram 100, graphite, diamond, liquid, and vapor can bethermodynamically stable forms of carbon. At low pressures, graphite canconvert into vapor around 4000K. In the carbon phase diagram 100,diamond synthesis from liquid carbon can require higher temperatures andpressures as the graphite, diamond, and liquid carbon triple pointoccurs at 5000K and 12 GPa, where 1 GPa is equal to 9869 Atm. Based onthe carbon phase diagram 100, diamond can exist in the interiors of theouter planets (e.g., Uranus and Neptune) and Earth's mantle, wherepressure and temperature are 600 GPa and 7000K, and 135 GPa and 3500K,respectively. In the carbon phase diagram 100, graphite can betransformed into diamond above about 2000K at 6 to 10 GPa using liquidmetal catalysts, which can be used for commercial synthesis of diamond.In some examples, carbon polymorphs can exist metastably well into apressure-temperature region, where a different phase isthermodynamically stable. As an example, diamond can surviveindefinitely at room temperature, where graphite is the stable form.

FIG. 1A also depicts a shift 104 in the carbon phase diagram 100. Insome examples, carbon can be melted at a low temperature (e.g., morethan 1000K less than the melting point of crystalline carbon). Meltingcarbon at a low temperature can create a highly undercooled state ofcarbon liquid, which can be of metallic nature. The highly undercooledstate can be created by irradiating the carbon using a nanosecond laser.The laser can be a nanosecond Excimer pulsed laser. For example, ananosecond laser pulse from the laser can melt the carbon and create thehighly undercooled state. Creating the highly undercooled state canmodify the carbon phase diagram 100. For example, creating the highlyundercooled state can cause the shift 104. The shift 104 can represent ashift in the carbon, diamond, and liquid carbon triple point. The shift104 can be a shift in the triple point from high-pressure andtemperature to low pressures and temperature. In some examples, thecarbon, diamond, and liquid carbon triple point can be shifted to 4000Kor lower at ambient atmospheric pressures.

In some examples, quenching or cooling the amorphous carbon from thehighly undercooled state to room temperature can create a phase ofcarbon. In some examples, the phase of carbon can be referred to asQ-Carbon. Q-carbon can be a state of solid carbon with a structure thathas a mixture of four-fold sp³ bonded carbon and sp² bonded carbon. Insome examples, the Q-carbon can have a structure that has a mixture ofmostly four-fold sp³ bonded carbon and some three-fold sp² bonded carbon(distinct entropy). The Q-carbon can have enhanced magnetic, mechanical,chemical, and physical properties, including, for example, enhancedroom-temperature ferromagnetism (“RTFM”) and enhanced field emission. Insome examples, the Q-carbon can be harder than diamond. For example,from covalent bond length determinations, the Q-carbon may be harderthan diamond (e.g., the Q-carbon can have a shorter averagecarbon-carbon bond length than diamond). In some examples, the relativehardness of the Q-carbon as measured by Hysitron Nanoindentor can beover 60% higher than that of diamond-like amorphous carbon.

In some examples, a subsequent laser pulse can be applied to theQ-carbon. The subsequent laser pulse can create a highly undercooledstate. Quenching or cooling the Q-carbon from the highly undercooledstate can cause graphene or various forms of diamond (e.g., diamondnanoneedles, microneedles, single-crystal films, nanodots, or nanorods)to form. Various forms of diamond can form from super undercooled stateof carbon depending on various factors, including, for example, thenucleation and growth times allowed for diamond formation. In someexamples, a nanodiamond can act as a seed crystal for growing amicrodiamond.

FIG. 1B shows thermodynamic Gibbs free energy variation as a function oftemperature for Graphite (G_(g)), Liquid Carbon (G_(liq)) and Diamond(G_(d)). It depicts equilibrium carbon melting temperature of T_(gi)(˜5000K) where liquid carbon free energy (G_(liq)) equals (G_(g)),T_(dl) (slightly above 4000K) where super undercooled carbon liquid canbe quenched into diamond in various nanostructures and microstructures,and T* (slightly below 4000K) where super undercooled carbon liquid canbe quenched into Q-carbon.

FIG. 2 is a top view of a scanning electron microscope (“SEM”)micrograph showing a cellular structure of a Q-carbon filament. In someexamples, the Q-carbon filament can be formed after a laser pulse isapplied to amorphous carbon. The amorphous carbon can be on a substrate,including, for example, a sapphire substrate, a plastic substrate, aglass substrate, or composite substrate consisting of copper/sapphire(“Cu/Sapphire”) or copper/titanium nitride/silicon (“Cu/TiN/Si”). Thelaser pulse can be provided by a nanosecond Excimer pulsed laser (e.g.,an ArF Excimer laser). The laser can have a wavelength of 193 nm. Thelaser can have a pulse duration of 20 nanoseconds (ns). The energydensity of the laser pulse can be 0.5 Jcm⁻². The Q-carbon filament canhave a size of 200 nm to 500 nm across. In another example, a similarmicrostructure of Q-carbon filament can be formed by applying a laserpulse with an energy density of 0.6 Jcm⁻² to the amorphous carbon. TheQ-carbon filament can have enhanced mechanical, chemical, and physicalproperties, including, for example, enhanced hardness, enhancedelectrical conductivity, enhanced room temperature ferromagnetism(“RTFM”), enhanced field emission (e.g., negative surface potential),and enhanced electron emission (e.g., negative electron affinity). As anexample, the Q-carbon can have enhanced ferromagnetism with a Curietemperature at about 500K. In another example, the Q-carbon can haveenhanced ferromagnetism with a Curie temperature over 500K. The Q-carbonmay have a density that is greater than the amorphous carbon. In someexamples, the Q-carbon can be harder than diamond. In some examples, theQ-carbon can have a matrix of mostly sp³ bonded amorphous carbon. Insome examples, nanodiamond nuclei or diamond nanocrystallites cannucleate from or be embedded within the four-fold coordinated (sp³bonded) Q-carbon. For example, FIG. 3 is an image showing formation of ananodiamond.

In some examples, the nanodiamond nuclei or lattice matching substratecan provide a seed for growth of nanodiamonds, microdiamonds, diamondnanoneedles, diamond microneedles, or large-area single-crystal diamondsheets. For example, FIG. 4 is a top view of an SEM micrograph showinggrowth of microdiamonds from a Q-carbon filament that containednanodiamond nuclei (e.g., the Q-carbon filament of FIG. 2). In theexample shown in FIG. 4, the Q-carbon filament can be formed by applyinga single laser pulse with a wavelength of 193 nm, a pulse duration of 20ns and an energy density of 0.6 Jcm⁻² to amorphous carbon. In someexamples, the microdiamonds formed from the Q-carbon can have a sizegreater than 100 nm. In the example shown in FIG. 4, the size of eachmicrodiamond can be between 500 nm and 600 nm.

In some examples, an area near the middle of the laser irradiatedamorphous carbon can include a high density of nanodiamonds andmicrodiamonds. For example, FIG. 5 is a top view of an SEM micrographshowing an area near the middle of an irradiated amorphous carbon thatincludes a high density of nanodiamonds and microdiamonds. In someexamples, a nanodiamond can have a size of less than 100 nm. In theexample shown in FIG. 5, each nanodiamond can have a size between 10 nmand 20 nm. In another example, nanodiamonds formed from a Q-carbon canbe of other sizes. For example, FIG. 6 is a top view of an SEMmicrograph showing formation of nanodiamonds from a Q-carbon. In theexample shown in FIG. 6, each nanodiamond can have a diameter between 2nm and 8 nm.

In some examples, an area near the irradiated amorphous carbon caninclude a high density of mostly microdiamonds. For example, FIG. 7 is atop view of an SEM micrograph showing an area near the middle of anirradiated amorphous carbon that includes mostly microdiamonds. In someexamples, microdiamonds may cover an entire area of the amorphouscarbon.

In some examples, a subsequent laser pulse can be applied to theQ-carbon. The subsequent laser pulse can cause nanodiamond formation onthe Q-carbon to grow microdiamond and nucleate other diamond structures.For example, a nanodiamond can provide, or act as, a seed crystal forgrowth of microdiamond. As an example, FIG. 8 is a top view of a SEMmicrograph showing a Q-carbon filament growing microdiamond through thegrowth of nanodiamonds. In some examples, a nanodiamond that acts as aseed for growth of the microdiamonds may exist on the Q-carbon filamentprior to the subsequent laser pulse being applied to the Q-carbon.

FIG. 9 is a top view of an SEM micrograph showing formation ofnanodiamonds by homogeneous nucleation and on top of existingmicrodiamonds formed by heterogeneous nucleation. In some examples,homogeneous nucleation may occur prior to applying the subsequent laserpulse to the Q-carbon. In some examples, heterogeneous nucleation mayoccur after the subsequent laser pulse is applied to the Q-carbon. Inthe example shown in FIG. 9, nanodiamonds 900, 902, 904, 906 can beformed by heterogeneous nucleation. In some examples, the nanodiamondsformed by homogeneous nucleation can be formed between the Q-carbonfilament. For example, FIG. 10 is a top view of an SEM micrographshowing formation of nanodiamonds by homogeneous nucleation betweenQ-carbon filaments. In the example shown in FIG. 10, the nanodiamondscan have a size between 10 nm and 20 nm.

In some examples various diamond structures can be formed from theQ-carbon. For example, nanodots and nanorods can form from the Q-carbon.As an example, FIG. 11 is a top view of an SEM micrograph showingdiamond nanodots and nanorods nucleating from Q-carbon. In someexamples, a laser pulse can be applied to the Q-carbon after theQ-carbon is formed from the amorphous carbon. The laser pulse may causethe Q-carbon to melt while microdiamonds on the Q-carbon may not melt.Melting the Q-carbon while not melting the microdiamonds can allow thediamond nanodots and nanorods to nucleate from the Q-carbon.

In some examples, most of a Q-carbon filament can be converted intomicrodiamonds or nanodiamonds. For example, FIG. 12 is a top view of anSEM micrograph showing microdiamonds forming when most of a Q-carbonfilament is converted into diamond.

FIG. 13 is a top view of an SEM micrograph showing a full conversion ofamorphous Q-carbon into a string of microdiamonds. In the example shownin FIG. 13, at least a portion of the Q-carbon may have microdiamondsembedded within the Q-carbon. In some examples, microdiamonds embeddedinto the Q-carbon within the Q-carbon may not be converted completelyinto diamond.

FIG. 14 is a top view of an SEM micrograph showing a triple point of aQ-carbon filament and the nucleation of diamond. In some examples, thetriple point of the Q-carbon filament may provide a site for enhancednucleation of nanodiamonds, microdiamonds, diamond nanoneedles, diamondmicroneedles, or large-area single crystal diamond sheets.

FIG. 15 is atop view of an SEM micrograph showing heterogeneousnucleation of nanodiamonds after a laser pulse is applied to theQ-carbon and diamond. In some examples, stepped and high-index surfaceson the Q-carbon may provide more nucleation sites for growth ofnanodiamonds, microdiamonds, diamond nanoneedles, diamond microneedles,or large-area single-crystal diamond sheets.

FIG. 16 is a top view of an SEM micrograph showing formation ofmicrodiamonds and some nanodiamonds after a laser pulse is applied tothe Q-carbon filament. In some examples, the nanodiamonds may nucleateon microdiamonds existing on the Q-carbon filament prior to applying thesubsequent laser pulse. In the example shown in FIG. 16, thenanodiamonds and microdiamonds may be of different morphology. Thenanodiamonds and microdiamonds may nucleate after two laser pulses areapplied to the Q-carbon. In some examples, each laser pulse can have anenergy density of be 0.6 Jcm⁻².

FIG. 17 is a top view of an SEM micrograph showing microdiamondscovering an entire region of a super undercooled carbon. In someexamples, nanodiamonds may form on top of the microdiamonds.

In some examples, a single-crystal diamond sheet can be formed from theQ-carbon. For example, FIG. 18 is a top view of an SEM micrographshowing formation of a large-area single-crystal diamond thin film. Insome examples, the large-area single-crystal diamond film can be dopedboth n-type (e.g., adding an impurity that contributes free electronsand increases conductivity) and p-type doping (e.g., adding an impuritythat can create a deficiency of electrons, known as holes). Doping thelarge-area single-crystal diamond thin film both n-type and p-type mayenhance the processing of high-power devices and high-power andhigh-temperature radiation resistant transistors.

In some examples, the large-area single-crystal diamond thin film can beformed when an epitaxial copper template is provided by usingCopper/Titanium Nitride/Silicon (“Cu/TiN/Si”) heterostructures. Inanother example, a copper template can be lattice matched with diamondin the absence of alloying effects for growing diamonds structures fromthe Q-carbon. For example, FIG. 19 is an image of an SEM micrographshowing diamond growing on a copper substrate, where diamond isepitaxially aligned with copper and grows as single crystal. The SEMimage depicted in FIG. 19 also shows an Electron Backscatter Diffraction(“EBSD”) from the underlying copper substrate and diamond microneedles.As another example, FIG. 20 is an image of an SEM micrograph showing theformation of a diamond faceted pillar 2002 from super undercooledcarbon.

FIG. 21 is a graph 2100 depicting an example of Raman spectra resultsfrom Q-carbon on a sapphire substrate after a laser pulse, according toone example. In some examples, the laser pulse can be a single laserpulse. The single laser pulse can be from an ArF Excimer laser. As anexample, the energy density of the laser pulse can be 0.6 Jcm⁻² and thewavelength of the laser pulse can be 633 nm. In graph 2100 a diamondpeak may occur at 1333 cm⁻¹ with a broad peak at about 1350 cm⁻¹ alongwith a small peak at 1140 cm⁻¹. In some examples, sp³ fraction ofbetween seventy-six percent and eighty-one percent can be obtained byfitting the Raman spectrum depicted in graph 2100. In graph 2100, peaksS₁ and S₂ (occurring at 1360 cm⁻¹ and 1375 cm⁻¹, respectively) maybelong to the sapphire substrate. In some examples, the graph 2100 mayalso indicate a slight upshift due to stress of the primary Raman peakand a bump at 1140 cm⁻¹, which may be characteristic of sp² bondedcarbon at the grain boundaries or interfaces in a nanodiamond. In someexamples, downshift in Raman peak may occur as the size of the diamonddecreases as a result of phonon dispersion relations.

FIG. 22 is a graph 2200 depicting an example of Raman spectra resultsfrom microdiamond on sapphire substrate after a laser pulse, accordingto one example. In some examples, the laser pulse can be a single laserpulse. The single laser pulse can be from an ArF Excimer laser. As anexample, the energy density of the laser pulse can be 0.6 Jcm⁻² and thewavelength of the laser pulse can be 633 nm. In graph 2200 a sharpdiamond peak may occur at 1331.54 cm⁻¹ along with sapphire peaks S₁ andS₂ (at 1360 cm⁻¹ and 1375 cm⁻¹, respectively). In some examples, thegraph 2200 may also indicate a small G peak of residual unconvertedamorphous graphite. In some examples, sp³ fraction of about fifty-twopercent can be obtained by fitting the Raman spectrum depicted in graph2200.

FIG. 23 is an image of a SEM micrograph image showing a cross-sectiontransmission electron microscopy (TEM′) sample of Q-carbon containingnanodiamonds and microdiamonds on a sapphire substrate, according to oneexample.

FIG. 24 is a high-resolution TEM (“HRTEM”) image showing a diamondmicrocrystallite and the corresponding <110> electron diffractionpattern, according to one example. The HRTEM image depicted in FIG. 24includes an image of cross-sections of the microcrystallite, whichdepict individual <110> columns of diamond.

FIG. 25 is a HTREM image from Q-carbon that has a substantiallyamorphous structure with some nanodiamonds embedded into the Q-carbon.

FIG. 26 is a graph of an electron energy loss spectroscopy (“EELS”)spectrum from diamond, according to one example. The EELS spectrumdepicted in FIG. 26 may contain a sharp edge at 288 eV with a peak at292 eV. In some examples, the sharp edge and peak may correspond to sp³bonding. The sp³ bonding may be characteristic of an EELS spectrum for adiamond.

FIG. 27 is a graph of an EELS spectrum from Q-carbon (e.g., the Q-carbondepicted in FIG. 25), according to one example. The EELS spectrum mayhave a sloping edge at 285 eV with a broad peak at 292 eV. In someexamples, the EELS spectrum may indicate sp³ bonding of about eightypercent. The sp³ bonding may correspond to Raman results from Q-carbon(e.g., the Raman results depicted in FIG. 21).

As described above, in some examples, a diamond nanoneedle ormicroneedle can form from Q-carbon. In some examples, a microdiamond maygrow from the Q-carbon in the form of a nanoneedle or a microneedle. Thediamond nanoneedle or microneedle may grow from Q-carbon in the absenceof any catalyst or in the absence of hydrogen. For example, FIG. 28 is aschematic diagram showing formation of diamond nanoneedle ormicroneedles 2802 from Q-carbon 2806. The Q-carbon 2806 can be formed bynanosecond laser melting of an amorphous carbon film 2804 and quenchingthe amorphous carbon film 2804 from an undercooled state to roomtemperature. In some examples, the carbon film 2804 can be on asubstrate 2808 (e.g., a sapphire, plastic, glass, Cu/TiN/Si orCu/Sapphire substrate).

FIG. 29 is an image of an SEM micrograph showing formation of diamondnanoneedles and diamond microneedles from super undercooled carbon. Inthe example shown in FIG. 29, an entire layer of amorphous carbon can beconverted into nanoneedles and microneedles.

FIG. 30 is an image showing EBSD Kikuchi patterns from microdiamondsgrowing out of super undercooled carbon, according to one example. Insome examples, a diamond microneedle or nanoneedle may grow from amicrodiamond on the Q-carbon. In the example shown in FIG. 30, a diamondmicroneedle 3002 may form from the Q-carbon. The microneedle 3002 mayhave a length of up to two microns. In some examples, the microneedle3002 may grow out of the Q-carbon formed near a sapphire interfacethrough carbon over layers. In some examples, the diamond nanoneedle andmicroneedle may grow from the Q-carbon in the absence of a catalyst. Inanother example, the nanoneedle and microneedle may grow in the absenceof hydrogen.

FIG. 31 is an image showing EBSD Kikuchi patterns from microdiamondsgrowing out of super undercooled carbon near a sapphire interface,according to another example. In the example shown in FIG. 31, a diamondnanoneedle or a microneedle 3102 may grow out of the super undercooledcarbon. As an example, a nanoneedle having a diameter of 80 nm can growout of the super undercooled carbon. In another example, a diamondmicroneedle having a diameter between 100 nm and 500 nm can grow out ofthe super undercooled carbon. In still another example, a diamondnanoneedle or microneedle having a length of up to 3000 nm can grow outof the super undercooled carbon

FIG. 32 is an image of an SEM micrograph showing diamond microneedles3202 forming from super undercooled carbon. In the example shown in FIG.32, the inset shows an electron backscatter diffraction pattern ofdiamond along with a characteristic diamond Kikuchi pattern.

FIG. 33 is a graph depicting an example of Raman spectra results fromdiamond microneedles (e.g., the diamond microneedles depicted in FIG.32). In the example shown in FIG. 33, the graph can indicate a sharpRaman diamond peak at 1136 cm⁻¹, where all the amorphous carbon isconverted into diamond.

FIG. 34 is an image of an SEM micrograph showing diamond nanoneedles andmicroneedles growing from super undercooled carbon on a sapphiresubstrate with inset EBSD and orientation diagram, according to oneexample.

In some examples, residual amorphous carbon can be etched away afterdiamond nanoneedles or microneedles form from the Q-carbon. For example,residual amorphous carbon can be etched away by oxygen plasma. Etchingaway residual amorphous carbon can provide more accurate data regardingformation of diamond nanoneedles or microneedles from Q-carbon. Forexample, FIG. 35 is an image of an SEM micrograph after residualamorphous carbon is etched away, which shows that nanoscale perturbationsets in quenched super undercooled carbon liquid. As another example,FIG. 36 is an image of an SEM micrograph after residual amorphous carbonis etched away, which shows formation of diamond nanoneedles andmicroneedles from Q-carbon. As still another example, FIG. 37 is animage of a SEM micrograph showing formation of nanoneedles andmicroneedles from super undercooled carbon phase after residualamorphous carbon is etched away, according to another example.

In some examples, etching away residual amorphous carbon can providemore accurate Raman spectra results (e.g., Raman spectra results withoutresidual amorphous peaks). For example, FIG. 38 is a graph depicting anexample of Raman spectra results from nanodiamond, microdiamond andlarge-area thin films without residual amorphous peaks.

In some examples, laser heating of amorphous carbon for forming Q-carboncan be confined spatially and temporally. Confining the laser heating ofthe amorphous carbon can allow diamonds or diamond films formed from theamorphous carbon to be deposited on heat-sensitive substrates (e.g.,polymer substrates or low thermal conductivity substrates, including,for example, sapphire, silicon, plastic, or glass). For example, FIG. 39is an image of a SEM micrograph showing microdiamonds and nanodiamondson a high density polyethylene (“HDPE”) substrate. In some examples, themicrodiamonds and nanodiamonds on the HDPE substrate can have an averagegrain size of 500 nm and 30 nm, respectively. In some examples, thediamond grains of the microdiamonds and nanodiamonds may containhigh-index facets. The high-index facets may have catalytic properties.In some examples, the high-index facets may provide nucleation sites forsubsequent diamond growth or formation.

FIG. 40 is a graph depicting an example of Raman spectra results beforeand after laser annealing an amorphous diamond-like carbon film. In someexamples, the carbon film can be irradiated with a laser pulse having anenergy density of 0.8 Jcm⁻². In the graph depicted in FIG. 40, a diamondpeak may occur at 1335 cm⁻¹ along with a HDPE peak at 1464 cm⁻¹ afterthe laser pulse is applied to the carbon film. In the graph depicted inFIG. 40, the Raman spectrum from the amorphous diamond-like carbon filmcan include a broad peak at around 1350 cm⁻¹. In some examples, sp³fraction of about forty-five percent before laser annealing can beobtained by fitting the Raman spectrum depicted in FIG. 40.

In some examples, a nanodiamond or microdiamond may form because ofdiamond phase from highly undercooled pure carbon. For example, for ahomogeneous nucleation of diamond from highly undercooled state of purecarbon, the Gibbs free energy of diamond nuclei (ΔG_(T)) consists ofgain in volume energy (ΔG_(V)) and expense of surface free energy(ΔG_(S)) terms. The Gibbs free energy of diamond nuclei ΔGT can bedetermined by solving the following formula:

ΔG _(T) =ΔG _(V) +ΔG _(S)

In the formula above, ΔG_(T) can be rewritten as the following formula:

${\Delta \; G_{T}} = {{\frac{- 4}{3}\pi \; r^{3}\frac{\rho}{M_{m}}\frac{\Delta \; H_{m}}{T_{m}}\Delta \; T_{u}} + {4\pi \; r^{2}r_{s}}}$

In the formula above, r, is the radius of diamond nucleus,

$\frac{\rho}{M_{m}}\frac{\Delta \; H_{m}}{T_{m}}\Delta \; T_{u}$

is the gain in free energy for the formation of diamond nucleus from theundercooled state of the pure carbon, T_(m) is the melting point ofcarbon, ΔT_(u) is the undercooling from the temperature of nucleation(e.g., a difference between T_(m) and the formation temperature(T_(r))), ρ is the solid diamond density. M_(m) is the molar mass,ΔH_(m) is the latent heat of melting, and r_(s) is the surface freeenergy between diamond nuclei and undercooling carbon liquid.

In some examples, the maximum of ΔG_(T), ΔG_(T)*, can correspond to thediamond reaction barrier at a critical size of the radius of diamondnucleus (“r*”). The ΔG_(T)* and r* values can be determined by solvingthe following formulas:

$r^{*} = \frac{2r_{s}T_{m}M_{m}}{{\Delta H}_{m}\Delta \; T_{u}\rho}$${\Delta \; G_{T}^{*}} = \frac{16\pi \; r_{s}3T_{m}^{2}M_{m}^{2}}{3\Delta \; H_{m}^{2}\Delta \; T_{u}^{2}\rho^{2}}$

In some examples, the rate of nucleation (l) can be governed by thefollowing formula:

$I = {A\; \exp \frac{{- \Delta}\; G_{T}^{*}}{{KT}_{r}}}$

in the formula above, T_(r)=T_(m)−ΔT_(u), A=n(kT/h) exp (−ΔF_(A)/kT), lequals the number of diamond nuclei cm⁻³s⁻¹, n equals the number densityof atoms, and ΔF_(A) is the free energy of activation across theliquid-solid interface. In some examples, a 5 nm and a 10 nm diamondcrystallite can have A values of 10²⁵ cm⁻³s⁻¹ and 10²⁴ cm⁻³s⁻¹,respectively. In some examples, the free energy of metastable diamond,highly undercooled carbon liquid, and amorphous diamond-like carbon canbecome equal at the formation temperature T_(r).

In some examples, a large value of ΔT_(u) can drive the critical size ofthe radius of diamond nucleus (r*) lower. Driving the critical size ofthe radius of diamond nucleus lower can enhance diamond nucleation. Inother examples, the value of ΔG_(T)* can be low, which may enhance thenucleation rate of a nanodiamond from the highly undercooled state ofcarbon. The nanodiamond may provide a seed for microdiamond growth.

FIG. 41 is a flow chart depicting an example of a process for convertingcarbon into a phase of carbon (e.g., Q-carbon) from which diamondstructures can grow or nucleate.

In block 4102, a laser pulse is provided to amorphous carbon. In someexamples, an amorphous carbon film can be irradiated with a nanosecondlaser (e.g., an ArF Excimer laser). The amorphous carbon can includebonding characteristics that may be a mixture of graphite (e.g., sp²bonded) and diamond (e.g., sp³ bonded). The amorphous carbon film may beirradiated with the nanosecond laser at room temperature in air atatmospheric pressure. In some examples, the nanosecond laser canirradiate the amorphous carbon film using a single nanosecond laserpulse. The wavelength of the pulse can range between 193 nm and 308 nm.The pulse duration can range 20 ns to 60 ns. In some examples, theenergy density of the laser pulse may vary. For example, the energydensity of the laser pulse can be 0.5 Jcm⁻² for forming a nanodiamond.In some examples, increasing the energy density of the laser pulse cancreate a microdiamond. For example, the energy density of the laserpulse can be 0.6 Jcm⁻² for forming the microdiamond. The laser pulse canmelt the amorphous carbon and create a highly undercooled state of theamorphous carbon. Undercooling the amorphous carbon can modify theequilibrium phase diagram of carbon (e.g., the carbon phase diagram 100in FIG. 1). For example, undercooling the amorphous carbon can shift thegraphite, diamond, and liquid carbon triple point on the equilibriumphase diagram from a high-pressure and temperature (e.g., 12 GPa and5000K) to low pressures and temperatures (e.g., ambient pressures andtemperatures in the range of 4000K). In some examples, shifting thegraphite, diamond, and liquid carbon triple point to low pressures andtemperatures may cause the Gibbs free energy of the amorphous carbon toequal the free energy of highly undercooled liquid and metastablediamond phase which is quenched and retained at room temperature. Insome examples, the amorphous carbon film can be on a substrate (e.g., asapphire, glass, or polymer substrate). Undercooling the amorphouscarbon can cause a highly undercooled carbon layer to form near thecarbon film-substrate interface.

In block 4104, the amorphous carbon is quenched. In some examples, theamorphous carbon film can be quenched and retained at room temperature.Quenching the amorphous carbon film from the highly undercooled state toroom temperature may create a phase of carbon (e.g., Q-carbon), whichcan grow a diamond structure.

In some examples, the Q-carbon can include nanodiamond nuclei which canprovide a seed for growth of a nanodiamond, microdiamond, diamondnanoneedle, diamond microneedle, or single-crystal diamond film. Inanother example, a subsequent laser pulse can be applied to theQ-carbon. The subsequent laser pulse can create a highly undercooledstate. Quenching or cooling the Q-carbon from the highly undercooledstate can cause a nanodiamond, microdiamond, diamond nanoneedle, diamondmicroneedle, or single-crystal diamond film to form.

In some examples, quenching the Q-carbon can cause a nanodiamond tonucleate. The nanodiamond can nucleate and provide a seed for growth ofmicrodiamond crystals. In some examples, the undercooled state may beretained for a sufficient period of time prior to quenching. Retainingthe undercooled state for a sufficient period of time can allow diamondnanocrystallites to nucleate and grow. As an example, for a nanodiamondhaving a size of 10 nm, the period of time for growth may be between 5ns and 10 ns. As another example, a diamond layer of unit cell thicknessof 0.356 nm may be formed by melting and quenching 37 nm of Cu-2.0 at %amorphous carbon film.

In other examples, nanodiamond nuclei can be embedded in the Q-carbon.The nanodiamond nuclei can provide a seed for growth of diamondmicrostructures, diamond nanostructures, and single-crystal diamondsheets. For example, the nanodiamond nuclei can provide a seed forgrowth of diamond nanoneedles, diamond microneedles, and large-areasingle-crystal diamond sheets.

In some examples, increasing the carbon content of the amorphous carbonfilm (e.g., from 2.0 at % to 4 at %) can double the thickness ofgraphene or diamond layers. In still another example, nucleation andgrowth of diamond or the formation of graphene from the amorphous carbonfilm can depend on a number of factors including, for example, theparameters of the laser (e.g., energy density of a laser pulse orduration of the laser pulse), the characteristics of the amorphouscarbon film substrate, the extent of undercooling of the amorphouscarbon film, and the sp³ content of the amorphous carbon film.

Q-carbon formed from the amorphous carbon film may have various enhancedcharacteristics and properties. For example, the Q-carbon can haveenhanced mechanical, chemical, and physical properties, including, forexample, enhanced hardness, enhanced electrical conductivity, enhancedroom-temperature ferromagnetism (“RTFM”), enhanced field emission, andenhanced electron emission (e.g., negative electron affinity). In someexamples, the Q-carbon can be harder than diamond. For example, fromcovalent bond length determinations, the Q-carbon may be harder thandiamond. In some examples, the Q-carbon may be a semiconductor. In otherexamples, the Q-carbon may be metallic. In still another example, theQ-carbon may exhibit robust ferromagnetism. As an example, the Q-carboncan have enhanced ferromagnetism with a Curie temperature at about 500K.In another example, the Q-carbon can have enhanced ferromagnetism with aCurie temperature over 500K.

FIG. 42 is a graph depicting an example of bulk ferromagnetism incarbon, according to one example.

FIG. 43 is a graph showing Kelvin Probe Force Microscopy (“KPFM”) onQ-carbon compared to a matrix of diamond and diamond-like carbon. In theexample depicted in FIG. 43, Q-carbon can have lower surface potential(e.g., up to 40 meV) compared to diamond-like carbon. In some examples,the lower surface potential can indicate that the Q-carbon has higherfield emission potential as compared to diamond-like carbon.

FIG. 44 is a graph showing resistivity of amorphous carbon versusresistivity of Q-carbon as a function of temperature. In some examples,resistivity of amorphous carbon can be measured before applying a laserpulse to the amorphous carbon. In the example shown in FIG. 44, therecan be a decrease in resistivity with increasing temperature after thelaser pulse is applied to the amorphous carbon (e.g., after the Q-carbonis formed). In some examples, the decrease in resistivity can indicatethat Q-carbon has characteristics of a semiconductor. For example, inthe example shown in FIG. 44, a decrease in resistivity with increasingtemperature can indicate that the Q-carbon may have semiconductingcharacteristics up to about 125K. The example shown in FIG. 44 may alsoindicate a semiconductor-to metal transition.

FIG. 45 is a graph depicting an example of Raman spectra results fromQ-carbon after multiple laser pulses. In the example depicted in FIG.45, the Raman spectra results may indicate that Q-carbon can be stableagainst thermal heating.

A diamond formed from Q-carbon may have various enhanced characteristicsand properties. For example, a nanodiamond formed from Q-carbon may haveenhanced hardness or enhanced electron emission and catalyticproperties. In some examples, a nanodiamond with enhanced electronemission properties may contain a sp³ bonded nanostructured diamond anda small fraction of sp² bonded carbon. The nanodiamond may also containdisordered carbon associated with grain boundaries.

Returning to FIG. 41, in some examples, the process for convertingcarbon into the phase of carbon further includes, in block 4106,integrating the diamond structure with a substrate. For example, thediamond structure can be integrated with a silicon based microelectronicdevice. In another example, the diamond structure can be integrated witha silicon based nanoelectronic device.

As an example, FIG. 46 is a flow chart depicting an example of a processfor integrating a diamond structure with a substrate.

In block 4602, titanium nitride can be grown on silicon. In someexamples, a layer of epitaxial titanium nitride can be grown on asilicon substrate. The titanium nitride can be grown by pulsed laserdeposition, for example, utilizing KrF (248 nm wavelength) or ArF (193nm wavelength). The epitaxial titanium nitride can have a latticeconstant of 0.42 nm. The silicon can have a lattice constant of 0.543nm. In some example, the layer of epitaxial titanium nitride can begrown on the silicon by domain matching epitaxy paradigm, where titaniumnitride can grow epitaxially on the silicon substrate. For example, theepitaxial titanium nitride can be grown on the silicon substrate withover twenty-two percent lattice misfit by alternating 4/3 (e.g.,corresponding to twenty-five percent misfit) and 5/4 (e.g.,corresponding to twenty percent misfit) domains of lattice planes withalmost equal frequency. In some examples, the epitaxial titanium nitridelayer can have low metallic resistivity (e.g., 15 μΩ-cm). In someexamples, the epitaxial titanium nitride layer with low metallicresistivity can provide an effective diffusion barrier and a templatefor epitaxial growth of subsequent function layers.

In block 4604 a carbon doped copper layer can be grown on the titaniumnitride. The copper layer can be grown by pulsed laser deposition, forexample, utilizing KrF or ArF. In some examples, the carbon doped copperlayer can have a lattice constant of 0.360 nm. The carbon doped copperlayer can be grown epitaxially on the titanium nitride by matching sevenlattice planes of copper with six lattice planes of titanium nitride,which may correspond to 7/6 domain matching epitaxy to accommodate overfifteen percent lattice misfit. In some examples, the epitaxial titaniumnitride layer can be a robust diffusion barrier layer, which can protectan underlying silicon substrate (e.g., the silicon substrate in block4102). For example, the epitaxial titanium nitride layer can protect thesilicon substrate from any contamination from the carbon doped copperlayer.

In block 4606, the carbon doped copper layer can be melted to formQ-carbon, which can grow a diamond structure. In some examples, thecarbon doped copper layer can be melted by pulsed laser annealing (e.g.,by utilizing a nanosecond Excimer pulsed laser). The carbon doped copperlayer can be melted by utilizing energy densities in the melting regime.In some examples, the melted carbon can be zone refined to surface andgrow epitaxially as graphene or diamond depending on parameters (e.g.,energy density) of the laser. The carbon doped layer can be melted toform Q-carbon, which can grow a diamond structure, in a mannersubstantially the same as the process for converting carbon intoQ-carbon described in detail with respect to FIG. 41.

In some examples, the diamond structure can be integrated with a siliconbased microelectronic device. In another example, the diamond structurecan be integrated with a silicon based nanoelectronic device. In someexamples the diamond structures can provide a template for the growth ofcubic boron nitride (“c-BN”).

In some aspects, methods for converting carbon into a phase of carbonwhich can grow or nucleate diamond are provided according to one or moreof the following examples:

Example #1

Diamond-like carbon films (e.g., amorphous carbon films) can bedeposited on sapphire (e.g., sapphire that is c-plane polished bothsides), SiO₂/Si(100) and glass substrates by using an ArF laser. The ArFlaser can provide a laser pulse for ablation. The laser pulse can have awavelength of 193 nm. The laser pulse can have an energy density of 3.0Jcm⁻² The ArF laser can provide the laser pulse for a duration of 20 ns.A second laser pulse can melt the deposited carbon films to a thicknessbetween 50 nm and 500 nm. The diamond-like carbon films can becharacterized by transmission electron microscopy and Raman spectra. Thediamond-like carbon films may be amorphous containing Raman signaturewith estimated Sp³ fraction over fifty percent. The diamond-like carbonfilms can be irradiated in air with ArF laser pulses. Each laser pulsecan have a wavelength of 193 nm. Each laser pulse can have an energydensity of 0.6 Jcm⁻². Each laser pulse can have a duration of 20 ns. Thediamond-like carbon films can be characterized by high-resolutionscanning electron microscopy, transmission electron microscopy, X-raydiffraction and Raman spectroscopy.

In some examples hexagonal boron nitride (′h-BN″) can be directlyconverted into cubic boron nitride (“c-BN”) by nanosecond pulsed lasermelting h-BN at ambient temperatures and atmospheric pressure in air.According to the pressure-temperature phase diagram of c-BN,transformation from h-BN into c-BN under equilibrium processing mayoccur at high temperatures and pressures, as the hBN-cBN-Liquid triplepoint is at 3500K/9.5 GPa or 3700K/7.0 GPa. By nonequilibrium nanosecondlaser melting h-BN, a super undercooled state can be created. The superundercooled state can shift the hBN-cBN-Liquid triple point to as low as2800K and atmospheric pressure. In some examples, h-BN can be directlyconverted into c-BN by controlling the kinetics of transformation atambient temperatures and atmospheric pressure in air by nanosecondpulsed laser annealing h-BN. In some examples, an n-type dopant and ap-type dopant can be incorporated into c-BN formed from h-BN.Incorporating a concentration of an n-type dopant (e.g., Si) and ap-type dopant (e.g., Zn or Be) into c-BN can create a doped layer. Thedoped layer can be used for next-generation solid state devices andsystems.

In some examples, c-BN can have enhanced properties. For example, a c-BNcoating may have less reactivity with ferrous alloys even at hightemperatures, which may allow the c-BN coating to be matched with theferrous alloys. In still another example, c-BN can be doped with bothn-type and p-type dopants. In some examples, a c-BN coating may have aprotective boron oxide layer. The protective boron oxide layer may causethe c-BN coating to have a higher oxidation resistance than diamond. Inanother example, the boron oxide layer can be an insulating layer, whichmay be used for solid state devices or systems (e.g., high-powerdevices, cutting tools, and biomedical applications). In some examples,c-BN may have properties, which may be advantageous over properties ofdiamond.

In some examples, c-BN may have properties similar to properties ofdiamond. For example, electrical properties of c-BN may be similar toelectrical properties of diamond.

FIG. 47 is a graph depicting an example of a cubic boron nitride phasediagram.

In the phase diagram depicted in FIG. 47, there can be differencesbetween well accepted Corrigan and Bundy (curve 1) and modificationssuggested by Solozhenko (curve 2) based upon some experimental bornnitride (“BN”) melting data and extrapolation of heat capacities of BNphases into high-temperature regime by using pseudo-Debye model, whichcan have at least four adjustable parameters.

In some examples, ΔG⁰ (T, P) for h-BN to c-BN phase transformation canbe negative in the temperature range 0-1600K and positive above 1600K.In some examples, ΔG⁰ (T, P) for h-BN to c-BN phase transformation beingnegative in the temperature range 0-1600K and positive above 1600K canmodify the well accepted phase diagram of Corrigan and Bundy, accordingto which c-BN line does not meet T-axis and intersects pressure axis at1.4 GPa. In some examples, the L-cBN-hBN triple point can be shiftedfrom 3500K/9.5 GPa (Corrigan-Bundy P-T diagram) to 3700K/7.0 GPa. Inanother example, the L-cBN-hBN triple point can be shifted from3500K/7.0 GPa to 3000K/0.1 MPa (1 Atm) by using nanosecond laser meltingto cause super undercooling of h-BN, where liquid BN can be directlyconverted into a stable phase of c-BN.

FIG. 48 is a graph depicting an example of Raman spectra results beforelaser annealing hBN and after laser annealing hBN. After laserannealing, only characteristic peaks for cBN are observed, illustrating100% conversion of hBN into phase-pure cBN, as shown in Table 2 below.Table 2 shows an agreement of Raman data with theoretical data on Ramanspectra of cBN.

Table 2, below, includes data from experimentally observed Ramanvibrational modes of cBN formed in accordance with the presentdisclosure. The theoretical and experimental values can be obtained fromab-initio calculations.

TABLE 2 Theoretical and experimentally observed Raman vibrational modesof c-BN Optical Branch Theoretical (cm⁻¹) Experimental (cm⁻¹) TO(X) 900902.15 TO(K) 910 917.82 TO(Q) 945 947.84 TO(W) 965 971.41 TO(Q) 1000998.27 TO( 

 ) 1035 1012.50 LO(K) 1075 1074.84 LO(L) 1140 1141.93 LO( 

 ) 1285 1310.88

FIG. 49A shows formation of super undercooled BN, which can be referredto as Q-BN, from which nano and micro cBN crystallites are formed. Insome examples, as-deposited hBN can be in the form of nanocrystallinehBN, which is melted at atmospheric pressure in air at an estimatedtemperature of 2800K. The Q-BN can be formed near a sapphire interface,similar to Q-carbon, which can break into filamentary structure throughinterfacial instability. In some examples, the Q-BN can be convertedinto nanocrystalline films, large-area <111> platelets, orsingle-crystal thin films. For example, FIG. 49B shows Q-BN convertedinto nanocrystalline films. FIG. 49C shows Q-BN converted intolarge-area <111> platelets. FIG. 49D shows Q-BN converted intosingle-crystal thin films.

FIG. 50A shows formation of nanoneedles and microneedles of cBN. In someexamples, some of the microneedles can be over two microns long.

FIG. 50B shows a mechanism of formation of nanoneedles and microneedlesof cBN, where interfacial instability in super undercooled BN leads toformation periodic features of an order of 90 nm, which coalesce to formlarger size microneedles.

FIG. 50C shows initial stages of formation of nanoneedles andmicroneedles as a result of interfacial instability.

FIG. 50D shows a large-area single crystal thin film formed in themiddle for a laser beam, where there is 100% conversion of hBN intophase pure cBN.

In some embodiments, hexagonal BN (“hBN”) can be deposited ontoc-sapphire substrates at room temperature using ArF laser (pulseduration=20 ns, wavelength=193 nm, energy density=3.0 J cm⁻²) in a laserMBE chamber under a vacuum of 3E-08 torr. The as-deposited films can benanocrystalline with grain size ˜25 nm. These films can be irradiatedusing pulsed ArF laser having energy densities of 0.3 to 1.0 J cm⁻² tocreate super undercooled BN (referred as Q-BN) from which nano- andmicro-cBN crystallites are formed. The as-deposited hBN can be in theform of nanocrystalline hBN, which can be melted at atmospheric pressurein air at the estimated temperature of 2800 K. The Q-BN is formed nearthe sapphire interface, similar to Q-carbon, which can break intofilamentary structure through interfacial instability. The Q-BN can beconverted into nanocrystalline films, large-area <111> platelets andsingle-crystal thin films, nanoneedles and microneedles of cBN. In someembodiments, large-area single-crystal thin films are formed in themiddle for the laser beam, where (0001) sapphire substrate is providinga template for (111) growth of diamond. In some embodiments hBN isconverted into phase-pure cBN in the form of nanodots, nanorods,microcrystalline thin films, and large-area single-crystal cBN thinfilms.

Embodiments also include methods for synthesis and processing of pureand/or nitrogen doped (or “N-doped”) diamonds (e.g., diamonds having anitrogen-vacancy (“NV”) center (or “NV defect”)) with sharp NV⁰ and NV⁻transitions at ambient temperatures and pressures in air. Pure andnitrogen doped nanodiamonds are non-toxic, and have enhanced electronic,magnetic, optical and mechanical properties with applications ranging,for example, from drug delivery and fluorescent biomarkers tosingle-photon sensors and quantum computing, nanoscale electronic andmagnetic sensing, single-spin nuclear magnetic resonance, nanoscalethermometry and nanosensors. The NV center in diamond is a point defectin diamond with C3v symmetry consisting of substitutional nitrogen andvacancy pair along <111> directions. Considering <110> chains, one ofthe links consists of a substitutional nitrogen and a lattice vacancy,as illustrated in FIGS. 51 and 52.

FIG. 51 illustrates the atomic structure of an NV defect in the <110>chains of diamond, and FIG. 52 illustrates the structure of an NV defectin the diamond tetrahedron contained in the half (a/2, a/2, a/2) unitcell. These NV centers in diamond are stable, and can be used, forexample, for reliable and robust electronic, optical and magneticnanoscale devices and systems operating at room temperature. The NVcenter is a deep-level defect; and it exists in neutral NV⁰ state andmagnetically active NV⁻ state with a trapped electron. Unique featuresof the NV center are derived from spin triplet ground state anddependence of fluorescence on spin orientation. The ElectronParamagnetic Resonance (“EPR”) spectrum of a single NV center can bedetected and shifts of the ERR spectra can be measured fromperturbations in electric and magnetic fields, temperature, spatialorientation, strain and pressure. The magnetically active NV⁻ defectsare characterized by optical zero phonon line (“ZPL”) at 1,945 eV (637nm), whereas NV⁰ has ZPL at 2.156 eV (575 nm). Associated vibronic bandsextend ZPLs to lower and higher energy absorption and emission.

The magnetically active NV⁻ is also characterized by zero-field magneticresonance at ˜2.88 GHz, which occurs between ms=0 and ms=±1 spins with ag-factor of 2.0028 associated with A₂ ground state. The opticallydetected magnetic resonance (“ODMR”) of NV⁻ at ˜1.42 GHz is attributedto ³E ground state with g-factor of 2.01. Because NV⁻ is magneticallyactive, its luminescence can be controlled by the magnetic field forvarious applications including, for example, single-photon sensors,nanoscale electronic and magnetic sensing, single-spin nuclear magneticresonance, nanoscale thermometry, fluorescent biomarkers, quantumcomputing and nanosensors. It may be desirable to perform controlledsynthesis of pure and NV-doped diamonds for these and/or otherapplications.

Embodiments include methods for controlled synthesis of NV-dopeddiamonds by direct conversion of N-doped carbon into NV-doped diamondstructures such as, for example, single-crystal nanodiamonds,nanoneedles, microneedles and/or thin films. In some such embodiments,one or more carbon films can be deposited by pulsed laser deposition ona substrate (e.g., tungsten carbide, silicon, stainless steel, titaniumnitride, sapphire, glass, or polymer substrate) to a desired thickness.In some embodiments, the layer thickness ranges from 5 nm to 500 nm. Thecarbon films can be doped with nitrogen by: (1) by adjusting thenitrogen partial pressure (5.0×10⁻³, 5.0×10⁻², 5.0×10⁻¹ Torr); and/or(2) by bombarding simultaneously with N₂ ⁺ (0.5-1.0 KeV) during carbonthin film deposition. The N₂ ⁺ ions break into atomic nitrogen atomsupon impact, which are buried inside the film. The nitrogenconcentration can be adjusted by controlling the nitrogen partialpressure and/or by measuring the nitrogen ion flux. Subsequently, thefilms are irradiated with high-power nanosecond laser pulses with energydensity 0.5-1.0 Jcm⁻², pulse duration 20-40 nanoseconds, and laserwavelength of 193 nm for ArF Excimer laser. The as-deposited and dopedfilms are melted in the highly super undercooled state and then quenched(e.g., within 200-250 nanoseconds) to form NV-doped diamond.

In some embodiments, the NV-doped diamond can be formed with dopantconcentrations exceeding solubility limits. Rapid quenching andsolidification (e.g., with velocity of the order of 5 ms⁻¹) from aliquid phase can trap NV defects beyond thermodynamic limits. Forexample, a single NV defect in 5 nm diamond may require solubility limitof 2.0×10¹⁸ Ncm⁻³, which can be achieved by rapid quenching (e.g.,within 200-250 nanoseconds) from the liquid, utilizing the phenomenon ofsolute trapping.

By controlling the quenching from the liquid, NV-doped diamonds can benucleated in the form of nanodiamonds (2-8 nm), microdiamonds (100-1000nm), nanoneedles and microneedles up to 3000 nm long, and large-areathin films. NV-doped nanodiamonds, microdiamonds, nanoneedles,microneedles, and large area single crystal films can be formed fromsuper undercooled carbon depending, for example, on the factorsdiscussed above and with values similar to those shown in Table 1.

In some embodiments, the NV defects can be located individually invarious diamond structures (e.g., as nanodiamonds (4 nm-10 nm),nanoneedles, microneedles and/or thin films) by, for example,controlling the nitrogen concentrations in the as-deposited films.Nitrogen is incorporated into the NV-doped diamond during rapidliquid-phase growth, where dopant concentrations can exceed thethermodynamic solubility limits, as discussed above. The number densityof NV defects can be controlled by the nitrogen concentrations in theas-deposited films. A single NV defect in 5 nm diamond may requiresolubility limit in excess of 2.0×10¹⁸ Ncm⁻³, which can be achieved byrapid quenching within 200-250 nanoseconds from the liquid, utilizingthe phenomenon of solute trapping. The NV-doped diamond can be formedwith sharp NV⁻ and NV⁰ transitions, and transitions between NV⁻ and NV⁰can be introduced electrically and optically by laser illumination.

In some embodiments, a single-crystal substrate template is used to growepitaxial NV diamond structures such as, for example, epitaxialsingle-crystal microdiamonds, nanoneedles, microneedles and large-areathin films.

In some embodiments, NV diamond structures can be placeddeterministically on the substrate. In some examples, the NV diamondstructures can be arranged periodically in a self-organized fashion(e.g., via self-assembly). In another example, strain driven placementcan be used to deterministically place NV diamond structures on thesubstrate.

Embodiments providing controlled doping of diamond with NV centers in avariety of nanostructures can be used, for example, for various quantumnanotechnologies in physical and biological sciences (e.g.,single-photon sensors, quantum computing, nanoscale electronic andmagnetic sensing, single-spin nuclear magnetic resonance, nanoscalethermometry, fluorescent biomarkers and nanosensors).

It will be appreciated that, in some embodiments, different dopants canbe used to create other types of doped diamonds, such as n-type andp-type doped diamonds. In some such embodiments, carbon films doped withan n-type dopant (e.g., Ni, P, As, or Sb—) can be directly convertedinto n-type doped diamond (e.g., n-type doped diamond with dopantconcentrations exceeding far beyond the thermodynamic solubility limits)similar to the methods discussed above with respect to NV-dopeddiamonds. It will similarly be appreciated that p-type doped diamond bydirectly converting carbon films doped with a p-type dopant (e.g., boronand boron compounds) can be directly converted into p-type doped diamond(e.g., p-type doped diamond with dopant concentrations exceeding thethermodynamic solubility limits).

Embodiments also include methods for controlled synthesis of pure (or“un-doped”) diamonds by direct conversion of pure carbon into purediamond. The pure diamonds can be in the form of single-crystalnanodiamonds, nanoneedles, microneedles and/or thin films. In some suchembodiments, one or more carbon films can be deposited by pulsed laserdeposition on a substrate (e.g., tungsten carbide, silicon, stainlesssteel, titanium nitride, sapphire, glass, or polymer substrate) to adesired thickness. In some embodiments, the layer thickness ranges from5 nm to 500 nm. Subsequently, the films are irradiated with high-powernanosecond laser pulses with energy density 0.5-1.0.1 cm⁻², pulseduration 20-40 nanoseconds, and laser wavelength of 193 nm for ArFExcimer laser. The as-deposited and doped films are melted in the highlysuper undercooled state and then quenched within 200-250 nanoseconds toform pure diamond. By controlling the quenching from the liquid, purediamonds can be nucleated in the form of nanodiamonds (2 nm-8 nm),microdiamonds (100 nm-1000 nm), nanoneedles and microneedles up to 3000nm long, and large-area thin films. Pure nanodiamonds, microdiamonds,nanoneedles, microneedles, and large area single crystal films can beformed from super undercooled carbon depending, for example, on thefactors discussed above and with values similar to those shown in Table1.

In some embodiments, a single-crystal substrate template is used to growepitaxial pure diamond structures such as, for example, epitaxialsingle-crystal microdiamonds, nanoneedles, microneedles and large-areathin films.

In some embodiments, pure diamond can be placed deterministically on thesubstrate. In some examples, the diamond structures can be arrangedperiodically in a self-organized fashion (e.g., via self-assembly). Inanother example, strain driven placement can be used todeterministically place diamond structures on the substrate.

With respect to FIGS. 53-66, the characterization of diamond phase wascarried by using electron backscatter diffraction (“EBSD”), Ramanspectroscopy (633 nm source), and photoluminescence (PL) with 325 nmsource. Alfa300 R superior confocal Raman spectroscope with a lateralresolution less than 200 nm was employed to characterize the Ramanactive vibrational modes. Crystalline Si was used to calibrate the Ramanspectra, which has its characteristic Raman peak at 520.6 cm⁻¹. Highresolution SEM with sub nanometer resolution was carried out using FEIVerios 460L SEM to characterize the as-deposited and the laserirradiated films. EBSD HKLNordlys detector with less than 10 nm lateralresolution was used to map out Kikuchi diffraction pattern in FEI Quanta3D FEG instrument in as-deposited and laser annealed thin films.

FIGS. 53-55 show high-resolution SEM micrographs of nanodiamonds frompure undoped samples. FIG. 53 is a high-resolution SEM micrograph ofnanodiamonds with inset at a higher magnification, according to oneexample. The example depicted in FIG. 53 shows the formation of undopednanodiamonds after a single laser pulse, where the average size variedfrom 2 nm to 8 nm, according to one example. These nanodiamonds nucleatefrom the highly undercooled carbon melt via homogeneous nucleation, andtheir size can be controlled by growth times during the quenching cycle.The larger sizes are formed as a result of heterogeneous nucleation,where sapphire acts as a template for diamond growth. Nanodiamonds arefaceted down to this size range, as shown in the inset.

During the initial stages or incipient carbon melting, the meltingoccurs in the form of rings, creating a ring of nanodiamonds, such asring 5402 shown in FIG. 54. FIG. 54 is a high-resolution SEM micrographof a mechanism of nanodiamond formation from Q-Carbon, according to oneexample. FIG. 54 also shows the formation of Q-carbon and nucleation ofnanodiamonds from Q-carbon, according to one example. The larger diamondmicrocrystallites grow from the melt with increasing growth time. Thenanodiamond growth around the super undercooled ring often has onelarger nanodiamond (e.g., 5404), which is formed when two nucleationfronts around the ring collide, as shown in the inset at a highermagnification. The larger micro-diamonds (e.g., 5406) can be formed whensapphire substrate provides a template for epitaxial growth from superundercooled liquid.

FIG. 55 is a high-resolution SEM micrograph of the formation ofnanodiamonds during initial stages and EBSD pattern, showingcharacteristic diamond Kikuchi pattern, according to one example. Theexample depicted in FIG. 55 shows the initial stages of the formation ofself-organized nanodiamonds, according to one example. The inset EBSDconfirms the diamond crystal structure, showing the characteristicKikuchi diffraction pattern for diamond. The formation of string likestructure in a supercooled liquid may be a result of spatialheterogeneity and dynamic facilitation in the regions having high atomicmobility, corresponding to high diffusivity in liquid of the order of10⁻⁴ cm²s⁻¹. Coherent motion of carbon atoms within micro strings mayfacilitate the creation of neighboring excitations leading to theformation of observed ring structure of liquid carbon from whichnanodiamonds can be formed. Molecular dynamics simulations have shownstring-like cooperative motion at temperatures well above the glasstransition temperature. The mean length of the string increases uponcooling with nearly exponential distribution with temperature.

FIGS. 56 and 57 show high-resolution SEM micrographs of microdiamondsfrom pure undoped samples. FIG. 56 is a high-resolution SEM micrographof a mixture of nanodiamonds and microdiamonds, according to oneexample. The example depicted in FIG. 56 is a high-resolution SEM ofundoped diamond nanocrystallites with average size 20 nm andmicrocrystallites with an average size of 500 nm, according to oneexample.

At a higher energy density, a full conversion of carbon into diamondmicrocrystallites is shown in FIG. 57, according to one example. Theinset at a higher magnification shows the details of faceting andtwinning in microcrystals. Such twinning in diamond can lead toimprovements in catalytic and mechanical properties. Embodiments canvary the twin content by controlling the quenching rates from the melt,as shown, for example, by the formation of twins in the inset. Thetexture and orientation of these microcrystallites can be controlled byproviding appropriate epitaxial template during growth from the liquidphase. In some embodiments, <111> oriented cubic diamondmicrocrystallites grow on (0001) sapphire, which are rotated withrespect to each other by 30 degrees. The growth of three-fold cubic<111> diamond on hexagonal (0001) sapphire leads to twinning as resultof two islands growing in a mirror symmetry.

FIG. 58 shows the formation of nanoneedles and microneedles as a resultof interfacial instability during growth from the liquid phase,according to one example. These nanostructures are single-crystalwithout any large-angle grain boundaries, as result of interfacialinstability during the initial stages of epitaxial growth with theunderlying substrate template. Single-crystal nature of diamond isdemonstrated by the Kikuchi diffraction pattern of the inset EBSD. Thelength of nanoneedles and microneedles is over three microns, which canoccur as result of liquid phase growth with velocities around fivemeters per second.

FIGS. 59 and 60 show high-resolution SEM micrographs of nanodiamondsfrom N-doped samples. In some embodiments, after laser annealing of theas-deposited nitrogen-doped carbon layers, nanocrystals with an averagesize of 4-8 nm are formed, as shown, for example, in the high-resolutionSEM micrograph in FIG. 59. FIG. 59 is a high-resolution SEM micrographof nanodiamonds, flat nanodiamond nanoplates, and perpendicularnanoplates of diamond with inset diamond EBSD Kikuchi pattern andorientation. FIG. 59 also shows the formation of diamond platelets, someof which grow flat (as shown by diamond platelet 5902) and others grownormal to the substrate (as shown by diamond platelet 5904), accordingto one example. The nanocrystals are faceted, which is similar to purediamond nanocrystals. The characteristic diamond EBSD (electronbackscatter diffraction) or Kikuchi pattern from a nanodiamond 5906 isshown in the inset, confirming the structure of the diamond phase andorientation. Assuming one nitrogen-vacancy complex (NV center) in 4 nmdiamond, the concentrations of N and V (3.0×10¹⁹ cm⁻³) exceedthermodynamic limit of 2.0×10¹⁸ cm⁻³ for nitrogen. Taking experimentalvalue for the formation energy of a neutral vacancy in diamond to be 3.0eV, the concentration is estimated to be ˜3.6×10¹⁹ cm⁻³ at 4000K. ThusNV centers with concentrations exceeding the solubility limits can beformed under quenching from the liquid through solute trappingphenomenon. The formation of two types of platelet crystals is alsoshown in FIG. 60. The faint contrast from flat diamond microcrystals isobserved because these are formed near the sapphire interface and areburied under the carbon.

FIG. 61 is a high-resolution SEM micrograph of microdiamonds fromN-doped samples containing twins. The example depicted in FIG. 61 showsa top view of a SEM micrograph showing formation of microcrystals ofN-doped diamond, according to one example. In this example,microcrystals are formed with (0001) sapphire providing a template forepitaxial growth by domain matching epitaxy. The epitaxial relations of<111> diamond on (0001) sapphire are as follows: in-plane 19 (2d110)planes of diamond match with 20 (d-2110) planes of sapphire.

FIG. 62 is a top view of a SEM micrograph showing formation of N-dopednanoneedles and microneedles, according to one example. From EBSDpatterns, these nanoneedles and microneedles are single-crystals withsizes up to 2-3 microns. Under the liquid phase growth, this willrequire crystal growth velocities of the order of five meters persecond, which have been established in silicon under highly undercooledstate during nanosecond laser annealing.

The Raman spectra from as-deposited carbon films as function ofincreasing nitrogen content (increasing partial pressure) are shown, forexample, in FIG. 63. The partial pressure of nitrogen was varied from5.0×10⁻³ Torr (for sample #1) to 50×10² Torr (for sample #2) to 5.0×10¹Torr (for sample #3). These Raman spectra contain D-peak at 1350 cm⁻¹and G-peak at 1550 cm⁻¹. The nitrogen incorporation is signified by: (1)increasing the intensity ratio of I(D)/I(G); and (2) shift in the G-peakto higher wavenumber 1565 cm⁻¹. The control sample with no-doping showsthe lowest D-peak. After laser annealing, the Raman spectra from N₂ ⁺implanted sample is shown in FIG. 64. FIG. 64 shows a sharp diamond peakwhich is downshifted from 1332 cm⁻¹ because of decreasing crystallitesize. Considering phonon dispersion relations, the downshift fornanocrystalline diamond may be expected, as the Raman active phonon isat the maximum frequency. The Raman spectra from nitrogen pressure-dopedsamples showed Raman peak around 1327 cm⁻¹, which is downshifted from1332 cm⁻¹, but also contained residual signature of G-peak around 1560cm⁻¹. The results of Raman downshift for different N-doped samples,varying from 3 to 5 cm⁻¹, are shown in FIG. 65. In this example, thereis an upshift due to stresses, which is combined with downshift due tosize. The Raman shift in diamond (Δω) is related to Δω (incm⁻¹)=2.2±0.10 cm⁻¹ GPa⁻¹ along the [111] direction, Δω (incm⁻¹)=0.73±0.20 cm⁻¹ GPa⁻¹ along the direction, and Δω (incm⁻¹)=3.2±0.23 cm⁻¹ GPa⁻¹ for the hydrostatic component. The biaxialstress in thin films can be described as a combination of two-thirdshydrostatic and one-third uniaxial stress. The biaxial stress can beestimated using σ=2μ((1+ν)/(1−ν))·ΔΣ, where μ is shear modulus, ν isPoisson's ratio, and Δε is the in-plain strain.

The photoluminescence spectra from these nanocrystal magnetically activeNV⁻ defects are characterized by optical zero phonon line (ZPL) at 1.945eV (637 nm), whereas NV⁰ has ZPL at 2.156 eV (575 nm). FIG. 66 shows aPL spectrum containing ZPL from NV⁻ (637 nm) and NV⁰ (575 nm) defects,with an inset (100× magnification) showing transitions when the sampleis irradiated with 532 nm PL source. FIG. 66 shows that magneticallyactive NV⁻ defects are characterized by optical zero phonon line (ZPL)at 1.945 eV (637 nm), whereas NV⁰ has ZPL at 2,156 eV (575 nm). Thesedefects may also exhibit associated vibronic bands, extending ZPLs tolower and higher energy absorption and emission. In some examples, thecharacteristic NV⁻ defect ZPL line from 5 nm diamond sample may beindicative of these defects being contained in the individualnanodiamonds, which can be used for variety of biomedical and nanosensorapplications. By using 532 nm PL source, it is possible to image in-situNV⁰ (575 nm) and NV⁻ (637 nm) defects and their transitions directly,as, shown in the inset of FIG. 66. The sharpness of PL peaks may beindicative of lack of other defects in nanodiamonds.

FIG. 67 provides the results on carrier concentration in N-doped diamondas a function of (VT). In some examples, the carrier concentration mayvary from 2.0×10¹⁸ to 5.0×10²¹ cm⁻³. These high concentrations may bethe consequence of dopant trapping during rapid quenching. In the caseof silicon, the dopant concentrations exceeding four hundred times thesolubility limits may be achieved as a result rapid solidification fromthe liquid phase. The phenomenon of formation of supersaturated siliconsemiconductor alloys was modeled by solute trapping concepts which canbe applicable in the diamond case as well. The carrier mobility as afunction of temperature for a sample with carrier concentration of2.0×10¹⁹ cm⁻³ is shown in FIG. 68, which shows Hall mobility as afunction of T. This corresponds to conductivity of ˜25 Ω/cm at 250 K,which, in some instances, may be reasonable. A fit to n=exp(−ΔE/k_(B)T)suggest ΔE ˜0.53 eV.

Pure and N-doped diamond nanostructures are created in the form ofnanodiamonds, microdiamonds, nanoneedles, microneedles, and large-areasingle-crystal thin films in a controlled way. This may be achieved byrapid melting of carbon in a super undercooled state and quenching toconvert carbon into diamond at ambient temperatures and pressures inair. The dopants such as nitrogen can be incorporated into diamond farin excess of solubility limit via solute trapping phenomena. The vacancyconcentration corresponding to quenching temperature can be trapped withnitrogen to create NV centers in nanodiamonds and other structuresexceeding the solubility limit. The NV⁻ and NV⁰ defects have beencharacterized by photoluminescence using 325 nm wavelength, and NV⁻ toNV⁰ transitions are controlled electrically by passing current and bylaser irradiation with 532 nm photons. Controlled synthesis andprocessing of NV nanodiamonds and other structures opens next generationof applications ranging from drug delivery and fluorescent biomarkers tosingle-photon sensors and quantum computing, nanoscale electronic andmagnetic sensing, single-spin nuclear magnetic resonance, nanoscalethermometry and nanosensors.

FIG. 69 shows a quantum spin phasemeter 6900 for magnetic fielddetection based on Q-Carbon, according to one example. Ferromagnetic(“FM”) Q-carbon can be used as a source of spin-injection to graphene(“Gr”) and/or a source of spin-detection from Gr. Quantum spinphasemeters with FM Q-carbon as a source of spin injection to Gr canhave various advantages such as, for example: long spin-relaxation timein Gr presumes high sensitivity, room temperature operation, nano-scalesize of the sensor, chemical inertness, and applications in biology andmedicine.

Embodiments include spintronic devices for use in detection of extremelyweak magnetic fields based on Q-Carbon. Such devices can include aone-terminal Q-carbon ferromagnetic (“FM”) gate 6902 with a graphenesheet 6904, which is terminated closed to a biased metallic contact6906, forming a capacitor which stores the electric charge Q under theappropriate electrical bias V_{g} and keeps the attendant spinpolarization P(t), which appears due to spin injection through the FMcontact at initial moment t=0. In operation, the injected spins canchange due to precession in a magnetic field and decoherence. When biasis reversed, the electrons leave the capacitor with rotated and reducedspin polarization so that the intensity of reversal current through FMgate depends on rotation of polarization and its magnitude. Thesedependences can be recorded applying the series of sequential measuringwith variable lengthening of exposure times (e.g., electron durationstay in the capacitor) at different device directions. Such measurementscan supply information about the strength and direction of an externalmagnetic field.

In some embodiments, Q-carbon can be an efficient spin injector. Forexample, spin polarization up to 35% has been observed for Co. Q-Carboncan also create an improved contact with graphene, which possesses verylong spin relaxation time at room temperature.

FIG. 70 shows a Q-Carbon as metallic ferromagnetic layer in aspin-torque oscillator, according to one example. Using a Q-carbon freelayer can reduce current that generates oscillations. Q-carbon can havemagnetic softness and a relatively low spin density compared withconventional metallic ferromagnets (magnetization M=66 emu/cm³ comparedwith M=580 emu/cm³ for Py and 1800 emu/cm³ for CoFe). As such, theQ-carbon can improve the performance of devices (e.g., tunnel magneticjunction (“TMJ”) devices) by substituting a metallic free FM layer witha Q-carbon layer. For example, smaller numbers of spin-polarizedelectrons switch magnetization when spin current passes through theQ-carbon layer. TMJ with Q-carbon can be used in memory devices as wellas in devices as a source of GHz oscillations.

FIG. 71 shows a Q-Carbon optical lock, according to one example.Q-carbon can provide durability under power laser light polarizationrotation. This can allow Q-carbon to be used as a Faraday locker, whichcan prevent spurious generation of next pulse before laser pumping is becompleted. As shown in FIG. 71, ferromagnetic Q-carbon can be used as aFaraday rotator 7102. The Faraday angle of linear polarized laser beamfrom laser 7104 can be tuned to 45 degrees, the reflection from thetarget 7106 will be rotated more on same angle and reaches 90 degrees.The perpendicular polarized reflection does not provoke a spuriousgeneration of next pulse before laser pumping will be completed.

FIG. 72 shows a Q-Carbon memory unit based on bistability underparamagnetic (“PM”)-ferromagnetic (“FM”) phase transition, according toone example. Carrier density (electro-chemical potential) increase canmediate transition from PM phase to FM phases. Such a phase transitioncan be accompanied with electronic system reduction that stabilizes FMphase. Magnetoresistance through the attached graphene layer 7206 candiscriminate Q-carbon PM 7202 or FM 7204 bistable states. Q-carbon maybe used as an electrically controlled magnetic memory cell based on, forexample, the magnetism of semiconducting Q-carbon's sensitivity tocarrier density.

FIG. 73 shows graphene, reduced graphene oxide and diamond integratedwith silicon and sapphire, according to one example.

Embodiments also include various uses for the materials and structuresdisclosed herein including, for example, coating the materials and/orstructures on aluminum, copper, zinc and zinc oxide coupons (contactsurfaces) of frequently activated electro-mechanical switches to reducewear and improve reliability, using the materials/structures asadditives to fuel to add horsepower, using the materials/structures asadditives to lubricants (e.g. motor oil) to reduce friction, coating thematerials/structures on the tips of bullets and missiles to increasepenetration, using the materials/structures in bulletproof fabrics andsurfaces, using the magnetic materials/structures to assist in drugdelivery by combining the materials with the drugs and magneticallydirecting to the desired part of the body; gemstones, coating thematerials/structures on cutting tool surfaces for increased hardness andlonger life, and using the materials/structures in brushless homopolarmotor for hypersonic jet engines.

FIG. 74 is a flow chart 7400 depicting an example of a process forquenching from a super undercooled state to form one or more structuresof material.

At 7402, a film is deposited. The film can be deposited on a substrate(e.g., tungsten carbide, silicon, copper, sapphire, glass, or a polymersubstrate). In some embodiments, the film is deposited on the substrateby pulsed laser deposition. In some embodiments, the film includesamorphous carbon and/or hexagonal boron nitride.

At 7404, at least a portion of the film is melted into a superundercooled state. In some embodiments, the film (or portion thereof) isirradiated with a nanosecond laser.

At 7406, the melted portion of the film is quenched from the superundercooled state.

In some embodiments, an amorphous carbon film is deposited at 7402 andquenching from the super undercooled state creates Q-Carbon, diamond,and/or Q-Carbon/diamond composite. In some such embodiments, thequenching can create Q-Carbon, diamond, and/or Q-Carbon/diamondcomposite based on the amount of undercooling achieved at 7404. Forexample, as shown in FIG. 1B and discussed above, at around temperatureT_(dl) (slightly above 4000K) super undercooled carbon liquid can bequenched into diamond in various nanostructures and microstructures, andat around T* (slightly below 4000K) super undercooled carbon liquid canbe quenched into Q-carbon. Diamond nanodiamonds, microdiamonds,nanoneedles, microneedles, or large area single crystal films can beformed by quenching from super undercooled carbon depending, forexample, on the factors shown in Table 1.

In some embodiments, quenching from the super undercooled state cancreate cubic boron nitride (e.g., when a hexagonal boron nitride film isdeposited at 7402).

The process can be repeated in whole or in part, as shown, for example,at 7408 and 7410, respectively, to melt and quench other portions of thefilm, and to deposit additional film(s) for processing.

FIG. 75 is a flow chart 7500 depicting an example of a process forquenching from a super undercooled state to form one or more structuresincorporating one or more dopants at concentrations exceedingthermodynamic solubility limits.

At 7502, a substrate is selected/configured. The substrate can beselected/configured to be a template for epitaxial growth and/or fordeterministic placement of structures to be grown on the substrate.

At 7504, a film is deposited. The film can be deposited on a substrate(e.g., tungsten carbide, silicon, copper, sapphire, glass, or apolymer). In some embodiments, the film is deposited on the substrate bypulsed laser deposition. In some embodiments, the film includesamorphous carbon and/or hexagonal boron nitride.

At 7506, at least a portion of the film is doped with one or moredopants. For example, the film can be doped with n-type and/or p-typedopants. In some embodiments, an amorphous carbon film is doped withnitrogen ions to form diamond with nitrogen vacancies at 7510.

At 7508 at least a portion of the doped portion of the film is meltedinto a super undercooled state. In some embodiments, the film (orportion thereof) is irradiated with a nanosecond laser.

At 7510, the melted portion of the film is quenched from the superundercooled state. The quenching can form one or more structuresincorporating dopants at concentrations exceeding thermodynamicsolubility limits.

In some embodiments, an amorphous carbon film is deposited at 7504 andquenching from the super undercooled state creates diamond incorporatingthe one or more dopants at concentrations exceeding thermodynamicsolubility limits via solute trapping.

In some embodiments, quenching from the super undercooled state cancreate cubic boron nitride (e.g., when a hexagonal boron nitride film isdeposited at 7504) incorporating the one or more dopants atconcentrations exceeding thermodynamic solubility limits via solutetrapping.

The process can be repeated in whole or in part, as shown, for example,at 7514 and 7512, respectively, to melt and quench other portions of thefilm, and to deposit additional film(s) for processing. In someembodiments, the process can be repeated at 7512 to add additionallayers of film with different dopant(s) than the previously quenchedfilm layer/portion (e.g., to create a PN junction) and/or to addadditional layers of film with the same dopant(s). In some embodiments,the process can be repeated at 7514 to melt and quench one or more otherportions of the film. In such embodiments, the other portions can bedoped with the same dopants as the previously quenched filmlayer/portion or different dopants.

Scaling up production can include repositioning between multiplequenching steps. For example, producing diamond structures can includecreating a first diamond portion, repositioning, and creating a seconddiamond portion adjacent the first to form, together with the firstportion, at least part of a nanodiamond, microdiamond, nanoneedle,microneedle, gemstone, large area single crystal film, or otherstructure. Those steps can be repeated until the complete structure ismade.

Repositioning can be accomplished by moving the first portion withrespect to an orientation of the laser pulse, moving the orientation ofthe laser pulse with respect to the first portion, or both. Moving thefirst portion can be done by translating or rotating a substratesupporting the first portion while leaving the orientation (angle) ofthe laser beam undisturbed so that a different portion of the substratepasses under the laser beam. Moving the orientation or scanning of thelaser beam with respect to the film can comprise rotating a servo-mirrorreflecting the laser beam onto a different portion of the substratewhile the substrate remains unmoved. Doing both could include moving thesubstrate surface and the mirror at the same time to achieve fasterrepositioning of the laser beam onto a separate portion of thesubstrate.

The present inventor has created Q-Carbon following procedures describedherein. The inventor conducted hardness testing on the created Q-Carbonusing Hysitron Nanoindentor. The hardness testing included pressing adiamond tip against the created Q-Carbon and diamond-like carbon in astandard hardness test. The diamond tip did not indent the createdQ-Carbon, indicating Q-Carbon is harder than diamond. Further, thediamond tip fractured when pressed against the created Q-Carbon,confirming Q-Carbon is harder than diamond.

The foregoing description of certain examples, including illustratedexamples, has been presented only for the purpose of illustration anddescription and is not intended to be exhaustive or to limit thedisclosure to the precise forms disclosed. Numerous modifications,adaptations, and uses thereof will be apparent to those skilled in theart without departing from the scope of the disclosure.

What is claimed is:
 1. A process comprising: doping boron nitride withn-type and/or p-type dopants, melting the doped boron nitride in anundercooled state; and quenching the melted boron nitride from theundercooled state to form n-type and/or p-type doped cubic boronnitride.
 2. The process of claim 1, wherein the boron nitride ishexagonal boron nitride.
 3. The process of claim 1, wherein the n-typeand/or p-type dopants are incorporated into electrically activesubstitutional sites of the created cubic boron nitride withconcentrations exceeding solubility limits via solute trapping.
 4. Theprocess of claim 1, further comprising: before the melting, depositingthe boron nitride as a film on a substrate.
 5. The process of claim 1,further comprising: using the substrate as a template for epitaxialgrowth of the created n-type and/or p-type doped cubic boron nitride. 6.The process of claim 1, wherein the created n-type and/or p-type dopedcubic boron nitride is a nanodot, microcrystal, nanoneedle, microneedle,or large area single crystal film.
 7. The process of claim 1, whereinthe melting comprises: melting the doped boron nitride in an undercooledstate by a laser pulse in an environment at ambient temperature andpressure.
 8. The process of claim 1, wherein the quenching comprises:quenching the melted boron nitride from the undercooled state to createn-type and/or p-type doped cubic boron nitride in an environment atambient temperature and pressure.
 9. A product formed by the process ofclaim
 1. 10. A process comprising: depositing a film of hexagonal boronnitride on a substrate; doping the hexagonal boron nitride film withn-type and/or p-type dopants, melting the doped boron nitride in anundercooled state by a laser pulse; and quenching the melted boronnitride from the undercooled state to form n-type and/or p-type dopedcubic boron nitride using the substrate as a template for epitaxialgrowth, the n-type and/or p-type dopants being incorporated intoelectrically active substitutional sites of the created cubic boronnitride with concentrations exceeding solubility limits via solutetrapping.
 11. A process comprising: depositing a film of hexagonal boronnitride on a substrate; doping at least a first portion of the hexagonalboron nitride film with first dopants, the first dopants being n-type orp-type dopants, melting at least a first portion of the doped firstportion of the hexagonal boron nitride film into an undercooled state bya laser pulse; quenching the melted first portion from the undercooledstate to form a first doped cubic boron nitride portion using thesubstrate as a template for epitaxial growth; doping at least a secondportion of hexagonal boron nitride with second dopants, the seconddopants being n-type or p-type dopants, the second dopants beingdifferent than the first dopants, melting at least a second portion ofthe doped second portion of hexagonal boron nitride into an undercooledstate by a laser pulse; and quenching the melted second portion from theundercooled state to form a second doped cubic boron nitride portion,the first and second dopants being incorporated into the created firstand second doped cubic boron nitride portions respectively atconcentrations exceeding solubility limits via solute trapping.
 12. Theprocess of claim 11, wherein the first and second doped cubic boronnitride portions together form at least a portion of a p-n junction. 13.The process of claim 11, further comprising: after the quenching themelted first portion, depositing a second film of the second portion ofhexagonal boron nitride.
 14. The process of claim 11, wherein the filmcomprises the second portion of hexagonal boron nitride.